Sadly for me, as it’s a product I find super useful, the Summify service will be shut down, according to a blog post describing the deal this morning.

Instead, five members of the Summify team will be joining Twitter’s growth team in San Francisco to help work on its products “to explore ways to help people connect and engage with relevant, timely news.”

Summify had started as an email service and extended to an iPhone app. One of its more novel features was that it focused on giving users less news instead of more, by sending users daily email summaries of only the most important stories. At the end of each day’s list it said “You’re done!”

The service picked those stories through a combination of how many times each user’s contacts had recently shared them on Twitter, Facebook and Google Reader, and how many times they had been shared on those networks globally.

Summify disabled new registrations today and dropped some features in anticipation of shutting down the service at an unspecified date.

Summify, which was started in Romania and based in Vancouver, had raised seed funding from investors including Accel Partners, Rob Glaser and Stewart Butterfield.

The arena for news readers on tablets and smartphones is competitive, with high-profile efforts such as Flipboard, Livestand from Yahoo, AOL’s Editions and start-ups such as Pulse and Zite.

The reason for CNN’s acquisition interest — as well as look-sees from several other publishers — is not a surprise: As readers turn more toward using these mobile devices to consume content, big media companies are trying to acquire the technology to serve up their fare to them.

It is a dicey arena, though, where content aggregation meets (and crashes into) content lifting. Vancouver-based Zite, for example, was sent a cease-and-desist letter in March, by a panoply of media companies (not CNN!) alleging various copyright violations.

That happened right after it was launched, with $4 million in funding from angel investors and Canadian grants and an innovative personalized article-picking algorithm.

As Liz Gannes wrote then:

[Then] Zite CEO Ali Davar describes the iPad as a way to “emancipate the technology” his team originated at research at the University of British Columbia.

It had previously been put to work in a browser plug-in called Worio. And, as you might have guessed, browser plug-ins are a tough business.

The free Zite app imports a user’s Twitter tweets, follows and Google Reader subscriptions, offers lists of pre-made categories, and then solicits feedback and refines over time a list of topics and sources the user is interested in. It features articles based on their popularity, number of shares from a user’s network and topic relevance. (Davar said he thinks a person’s Facebook network data is too heterogeneous to reliably recommend articles, so it’s not included as an option.)

Last week, a Canadian site called Techvibes first wrote about the possibility of the sale of Zite to CNN, which is based in Atlanta and owned by Time Warner.

In a press release, CNN said Zite would remain a standalone unit, as a wholly-owned subsidiary of CNN, and that CEO Mark Johnson will continue to run Zite’s operations, but now in San Francisco. CNN also said that Davar will remain an executive director and Mike Klass will continue as CTO.

In a statement, Johnson said: “Zite is thrilled about combining forces with CNN to create a world-class news discovery platform. In CNN, we have found a partner who shares our vision and passion. Being part of the CNN family gives us the capital to grow Zite’s business and continue to innovate in the space.”

A panoply of big media giants sent a cease-and-desist letter today to Zite, the Apple iPad news reader app.

The Washington Post, AP, Gannett, Getty Images, Time, Dow Jones and many other media organizations were part of the action, which you can read all about below.

Zite bills itself as a “personalized iPad magazine that gets smarter as you use it.”

Not smart enough, it seems, to avoid copyright complaints from the content creators the app sucks in.

“The Zite application is plainly unlawful,” said the letter to Zite CEO Ali Davar, noting all kinds of copyright violations.

In a phone interview with BoomTown this afternoon, Davar said Zite would comply with the letter by shifting the content from its “reading” mode to a Web one, which points to publisher sites.

“It’s a bummer that they did this, but we expected it,” he said.

In a comment he posted below, Davar also wrote:

“Zite’s goal is to work with publishers, not to be antagonistic. The few publishers that have contacted us regarding the reading mode view we have complied with their requests and simply switched over to web view. We’re talking to publishers right now to find a win-win for them monetarily and to at the same time preserve the great user experience.”

For now, it’s lose-lose, and the letter is a dramatic shot across the bow of all the many news readers now hitting the market in the wake of the popularity of the Apple iPad tablet.

The social media-focused Flipboard and the news-oriented Pulse are two others, both of which have claimed they are working with publishers.

But Pulse wrangled with the New York Times over misuse of its RSS feeds and copyright issues, which has since been settled.

Zite showed up earlier this month, a product of a machine-learning technology start-up called Worio, which is based in Vancouver, Canada.

The aggregator of personalized content, which has $4 million in angel funding, gets its cues from a user’s interests.

Zite’s technology originated at research at the University of British Columbia several years ago.

In an interview with NetworkEffect’s Liz Gannes a few weeks ago, Davar seemed sanguine about publishers.

Wrote Gannes:

The free Zite app imports a user’s Twitter tweets, follows and Google Reader subscriptions, offers lists of pre-made categories, and then solicits feedback and refines over time a list of topics and sources the user is interested in. It features articles based on their popularity, number of shares from a user’s network and topic relevance. (Davar said he thinks a person’s Facebook network data is too heterogeneous to reliably recommend articles, so it’s not included as an option.)

Flipboard itself is likely to add more personalization features; the company bought real-time social discovery technology from Ellerdale and has yet to implement much of it.

Vancouver-based Zite is well-funded, with $4 million from angels and Canadian grants, but it doesn’t have business relationships with publishers. The app lays out pictures and articles, stripping out everything else, including ads. Davar said he doubted this would be a problem. “It would be shortsighted for publishers to think of Zite as us versus them,” he said.

Short-sighted maybe, but legally lethal definitely, as you can see by this cease-and-desist letter, as well as a video from Zite on how its app works:

Letter to Zite _03 30 11_ –

Zite: Personalized Magazine for iPad from zite.com on Vimeo.

(Full disclosure: New Corp. owns Dow Jones, which owns this site.)