Was TweetDeck's Sale a Good Deal? That Depends on Bill Gross.

On paper, Twitter is worth $4 billion. Its investors, at least, believe it will be worth $10 billion sooner than later.

So why is the leading Twitter application–the one that many of Twitter’s most ardent users rely on–selling itself for $30 million?

That’s the question lots of people are mulling over since Friday’s news about the UberMedia/TweetDeck deal.

The tech investors and observers I’ve chatted with in the last couple of days generally land in one of two camps. Either:

• TweetDeck is the biggest Twitter client not owned by Twitter, and they sold too early.
• TweetDeck is the biggest Twitter client not owned by Twitter and, given the circumstances, they did okay.

This is basically a more muted replay of last year’s Twittersphere freakout, when it became clear that Twitter wanted to own much more of the Twitter ecosystem itself, and would place more limits on everyone else.

One important variable here is the way you view Bill Gross and UberMedia. A big chunk of the TweetDeck payout–the majority, according to multiple sources–will be in UberMedia stock. So if you think that company–which just raised another $17.5 million itself–has an upside, then the deal looks that much better.

That’s hard to figure, though, because Gross seems to be doing two things: Buying Twitter apps that compete with Twitter’s own products, and building a Twitter advertising system that will compete with the one Twitter is trying to build itself.

And Twitter doesn’t seem any more receptive to any of that now than it did 10 months ago. But Gross and his backers argue that they’re going to pull it off in a way that makes Uber become the Zynga to Twitter’s Facebook–a smaller company built on another bigger company’s platform, that makes both of them more valuable. So if they’re right…

Meantime, this seems like a good time to revisit Twitter investor Fred Wilson’s “inflection point” essay from last April.

That’s the one that precipitated much quaking among third-party Twitter developers and investors, with good reason: In part, it explained that Twitter would be buying or building “hole-filling” services, which meant there wouldn’t be much reason for many of the Twittersphere’s existing apps to exist.

A year later, though, it’s the second part of Wilson’s essay, where he calls on developers to build new apps and services that “create something entirely new on top of Twitter,” that seems more striking.

Because if Twitter really does end up being worth $10 billion or more, it seems like someone ought to be trying to do that. I’m not sure I’ve seen any, though.

Am I missing something? Feel free to weigh in below.