Microblogging site Twitter has announced that it's going to be buying up 3rd-party iPhone app Tweetie and making it official, turning it into "Twitter for iPhone". The app will also be made free.

The reasoning, Twitter says, is that a pile of users were searching for an official Twitter app in the iTunes App Store, and giving up after they couldn't find one. As a result, the company reckons that by providing one it'll be able to grab itself a whole load of new users. "People everywhere should be able to access Twitter without friction or confusion", says the company.

Tweetie currently costs $3, but as part of the official takeover, it'll be made free. The chap who designed it, one Loren Brichter, will join Twitter as a member of its mobile team, and begin work on Twitter for iPad, which doesn't yet have a release date.

Twitter said, in a blog post, "As we work to provide the best possible Twitter experience on all of the major mobile platforms, momentum will increase dramatically. Millions more active, engaged, mobile users means more opportunities for all of us".