There’s some speculation this weekend over the reasons why Twitter suspended three third-party mobile apps on Friday.

Ubertwitter (now known as Ubersocial), Twidroyd and Ubercurrent were all suspended due to what Twitter described as “policy violations.”

What this means from the user point of view is that if you use any of these apps on your mobile device, it doesn’t update your tweets any more, neither the ones to and from your community, nor ones mentioning you or private messages. And you can’t send any yourself either.

My third-party app of choice on my Android mobile devices is Twidroyd. I noticed yesterday morning that nothing would update, as this screenshot I made today shows – you can see the date of last updates as February 18.

Note, too, the top two tweets: official communication from Twitter, one suggesting I get an official Twitter client, and the other with a link to their explanation on why the suspension happened:

Regardless of how you access Twitter, we are dedicated to making Twitter better, faster and more reliable for you. As part of this effort, we ask applications that work with Twitter to abide by a simple set of rules that we believe are in the interests of our users, and the health and vitality of the Twitter platform as a whole. We often take actions to enforce these rules.

We have suspended UberTwitter and twidroyd for violating our policies.

Every day, we suspend hundreds of applications that are in violation of our policies. Generally, these apps are used by a small number of users. We are taking the unusual step of sharing this with you because today’s suspension may affect a larger number of users.

The bold text is my emphasis as I think this is a significant aspect of this disagreement between Twitter and Ubermedia, the company that owns all three of the suspended apps.

According to a Flash image display on Ubermedia’s website, their apps – which, incidentally now also includes TweetDeck, which isn’t affected by this ban – are used by three million Twitter users; and, to put it another way, account for 20 percent of all tweets sent every day, according to Seesmic founder Loic Le Meur. Those certainly are large numbers by anyone’s measure.

So from Friday, three million people potentially couldn’t use Twitter all of a sudden. That’s quite an effect. Many no doubt did as Twitter suggested or, as I did, load up a third-party alternative such as TweetDeck for Android/iPhone/iPad or Seesmic mobile for multiple platforms.

There’s a Quora discussion in which Ubermedia CEO Bill Gross outlines three reasons he says Twitter gave him for the suspension, involving privacy issues, affiliate linking and renaming Ubertwitter. Gross also spoke to TechCrunch on Saturday, where he said:

[…] UberTwitter will change its name to UberSocial. The privacy issues are related to handling Tweets longer than 140 characters. And the monetization issue, Gross believes, has to do with Twitter’s belief that UberMedia is using affiliate links, which he says it is not. But he is eager to comply with Twitter’s requests and be back in its good graces. “Whatever it is we will change it,” he says.

As I really miss Twidroyd, I’m taking some encouragement both from Gross’ comments to TechCrunch as well as a tweet from Twidroyd that a new “Twitter compliant” version is coming soon.

Whatever’s behind this – Twitter applying some market pressure on a company that now owns a significant part of the overall Twitter ecosystem or just to do with policy violations – it’s happening over a weekend when many people are offline. I wonder what things will look like on Monday morning if this is still unresolved.

[Update Mon Jan 21] New versions of Ubersocial and Twidroyd have been written and approved by Twitter, says TechCrunch. I don’t know about Ubersocial but I can verify that new version 5.0.2 of Twidroyd is now in the Android Market: I just installed it and sent a tweet. So things are working again.