Palm could have succeeded on its own–but only as a small company, Rubinstein says. It wouldn’t have been able to really compete with Apple, Google and the rest of the market.

Here’s Rubinstein at D: Dive Into Mobile explaining to Kara Swisher Palm’s decision to sell: “The market moved too fast, as far as competition went… what we didn’t see was a way to get to scale…. We could have been a small, successful company, but I don’t think that’s long-term sustainable in this business.”

More in-progress coverage here from our liveblog.

Two years later, Palm no longer has a share price, having been acquired by Hewlett-Packard, and Rubinstein, no longer its CEO, runs HP’s new mobile devices unit. But with the iconic Silicon Valley company backing it and “doubling down on webOS” and a new tablet based on the OS headed to market, its future is perhaps equally as promising, if not more so.

2:57 pm:
The session kicks off with video of a previous interview with Rubinstein in which he–the “father of the iPod”–claimed never to have used an iPhone.

So, have you touched an iPhone yet? Kara asks.

Rubinstein laughs. “Oh, we’re going to go through this again? Have I used one as my own device? No. Have I touched one? Yes.”

2:58 pm: Rubinstein continues: For me personally, we have lots of people who use iPhones and we have competitive analysis groups who review competing products, but I don’t want to be tainted by another experience. I want to come at this with a fresh perspective and I think what we’re seeing now in this industry is that everyone is copying the iPhone.

3:00 pm: Sorry, we’re having some connectivity issues here….

Moving on now to Palm and its ultimate acquisition by HP.

I think we did have many of the elements to be successful. We had a great team, a great product, a great product pipeline….But I think the market moved too fast and when we looked forward we saw a very clear way to where we could get the company to profitability, but we didn’t see a way to get it to scale….We could have been a small, successful company, but I don’t think that’s long-term sustainable in this business.”

So it was an issue of scale and not the “creepy lady marketing?” Kara asks.

Rubinstein says no, though he concedes the Palm Pre could have been marketed better.

3:04 pm: Ultimately, says, Rubinstein, we just ran out of runway…. We looked at a variety of different alternatives, and at the end of the day we decided that the best thing to do was to hook up with a partner that could get webOS to scale….The most expeditious outcome was to partner with HP.

3:05 pm: What other companies were interested in acquiring you? Kara asks. Rubinstein won’t say. What he will say is that the one that made the most sense was HP. “They didn’t have a great mobile strategy, but they had the means to get webOS to scale….A company like HP needs to be in control of its own strategy….This is not ‘game over.”

3:07 pm: How badly did HP need Palm? “Look,” says Rubinstein, “HP is the largest computer company in the world…it needs a mobile strategy. And it needs a mobile OS of its own….They needed to be in this space, and now they’re very jazzed about webOS.

3:08 pm: How about the Mark Hurd scandal? Was it much of a distraction for Palm? Rubinstein says it wasn’t. Palm was relatively new to the company when it occurred and was thus unaffected. “There was some turmoil for a few days,” he says. “That’s about it.”

3:10 pm: Moving on now to Palm’s role within HP. “What we chose to do as part of the acquistion was to integrate part of Palm into HP and keep part of it separate….The engineering team is essentially separate…things like HR and finance are handled by HP….From my perspective, what we were planning on doing and what HP wanted to do were very well aligned.”

Post acquisition, says Rubinstein, as soon as we aligned our road maps, we were off and running. He notes that internal relationships with divisions like HP Labs have been quite helpful.

Will the Palm name continue? asks Kara.

[Sorry, more connectivity problems.]
Rubinstein: That’s something we’re debating. What do you think we should do?

Kara: Get rid of it.

Rubinstein: Okay [jokingly]….I don’t really have much of a connection to the Palm brand.

3:16 pm: What’s Rubinstein’s view on the competitive environment? “Look, this is a huge market. The growth is phenomenal. If we roll back three years to when I started this Palm adventure, mobile was the place to be. And it still is today. I think we still have the chance to become a major player if we do the right things.”

3:20 pm: What’s the more important device, the phone or the tablet? asks Kara. Rubinstein says he doesn’t think people will have just one device. “It used to be that people shared a device. These days, people have multiple devices. So the new question is how do these devices interact so there’s a seemless user experience across devices….The ability to have a unified experience on all your devices is very important.”

3:21 pm: The conversation moves on to carrier relationships. Rubinstein observes that AT&T is doing pretty well in the Bay Area. “Just for you,” quips Kara.

3:23 pm: And on to the Q&A. First question from Engadget’s Josh Topolsky. What’s the Palm story that’s going to make people buy your phones? How do you convince a consumer to buy your stuff when you’re competing with the likes of Google and Apple?

Rubinstein: We really do have a unique experience compared to everyone else….The other concept around this is the connected device strategy. We’re in this transition now where we’re integrating into HP, so we’re still ramping up.

3:25 pm: Kara circles back, asks about differentiation and how HP can break through all the marketing noise. Where do you think the next radical change in the mobile market is going to come from? she asks.

I think it’s going to be incremental change, not a radical. I think it’s all about bringing this vision of a more connected world to our users.

Kara asks about forthcoming webOS devices.

Rubinstein gives the standard answer: “Stay tuned.” But he added, “This will be a very different conversation next year.”

3:25 pm: And that’s it.

Tonight, All Things Digital will debut its first extension of the D: All Things Digital conference, with D: Dive Into Mobile.

The original nickname for the event was “mini-d,” since it is shorter than big-D, focused on one key topic and has a more intimate audience.

But the speakers Walt Mossberg and I have assembled are anything but small on the critical topic of mobile–beginning with tonight’s opening session with Google Android kingpin Andy Rubin.

There is a lot to talk, about from monetization of the ever-popular operating system to its rivalry with the Apple iPhone to its relationship with wireless carriers.

D: Dive Into Mobile continues all day Tuesday, with speakers that include: Dan Hesse, President and CEO of Sprint Nextel; Mike Lazaridis, co-CEO of Research in Motion; Mike McCue, CEO of Flipboard; Joe Belfiore, Vice President of Windows Phone Program Management at Microsoft; Jon Rubinstein of Palm, now owned by Hewlett-Packard; Foursquare CEO and co-founder Dennis Crowley; Google Ad Products Management head Susan Wojcicki; AT&T Emerging Devices President Glenn Lurie; and Spotify CEO Daniel Ek.

D: Dive Into Mobile is being held at the Ritz-Carlton in San Francisco and, as usual, we’ll be liveblogging the whole thing and also posting highlight videos.

Along with Mossberg and me, Mossberg Solution’s Katherine Boehret and MediaMemo’s Peter Kafka will be conducting the interviews.

For more information, click here for D: Dive Into Mobile news and more.

And we’ve just added an exciting new speaker to the already top-drawer list: Daniel Ek, co-founder and CEO of Spotify.

For those living under a rock, Ek (pictured here with co-founder Martin Lorentzon) leads one of the most exciting music services on the Web right now.

In fact, the Swedish entrepreneur is shaking up how and where people listen to and consume music.

As MediaMemo’s Peter Kafka–who will be interviewing Ek onstage–recently wrote of Spotify’s efforts to bring its hugely popular (and legal) streaming offering to the U.S. market:

In Europe, where Spotify has been a very big success, listeners can stream an unlimited amount of music, on demand, without ever paying a cent. But in the U.S., rival streaming services like Rhapsody, MOG and Napster generally only offer a very brief trial period of a few days before requiring that a pay wall go up.

For the past two years, Spotify has insisted that free, unlimited streaming is the only way the service will work, because that’s Spotify’s most effective marketing technique. Subscribers who do pay up get benefits like ad-free music, and the ability to port their songs to mobile devices like iPhones.

But the labels, most notably Warner Music Group, have insisted that unlimited free streams only serve to strip away their product’s remaining value–if you can listen for free on Spotify, why would you ever buy another CD or iTunes single?

The whole mobile music space is a riveting one to dive into, of course, and we think Ek is the perfect person to help us do so.

Ek will appear Tuesday morning, December 6, but D: Dive Into Mobile opens on Monday, December 6, with an evening onstage interview with Google Android majordomo Andy Rubin.

The new conference represents the very first brand extension of our D: All Things Digital conference, now in its ninth year of grilling the big names in tech and media to sold-out analog audiences and scores more on the Web.

And, as always, there will be no PowerPoints, no panels and definitely no pontificating.

What there will be are unrehearsed, unscripted and unexpected interviews with top players, taking a big-picture view of the broader digital landscape.

But, unlike big D, D: Dive Into Mobile is topic-focused, drilling down deeply into the ubiquity of mobile technology and devices, and its implications for brands, organizations and consumers worldwide.

Offering a more intimate and focused conference setting, D: Dive Into Mobile will feature other industry heavyweights, including: Dan Hesse, President and CEO of Sprint Nextel; Mike Lazaridis, co-CEO of Research in Motion; Mike McCue, CEO of Flipboard; Joe Belfiore, Vice President of Windows Phone Program Management at Microsoft; Jon Rubinstein of Palm, now owned by Hewlett-Packard; Foursquare CEO and co-founder Dennis Crowley; Google Ad Products Management head Susan Wojcicki; and AT&T Emerging Devices President Glenn Lurie.

D: Dive Into Mobile will be held at the Ritz-Carlton in San Francisco and, as usual, we’ll be liveblogging the whole thing and also posting highlight videos.

Along with Walt Mossberg, Kafka and I, Mossberg Solution’s Katherine Boehret will be conducting the interviews.

You can sign up here for D: Dive Into Mobile.