We posted about Doubletwist earlier this year -- it's a pretty innovative music app (developed in part by Jon Lech Johansen, otherwise known as DVD Jon) that not only plays you play whatever you like, obviously, but even lets you share and send music off to anyone, even other people who don't have the app itself. Now Doubletwist is stepping up even more closely to becoming an iTunes competitor: they've announced a partnership with the Amazon music store to sell music directly from within the app. No TVs or movies -- just music, purchased directly within the app, and then able to be sent out to any devices or social networks as usual.

TechCrunch says the store's simplicity is actually a selling point -- iTunes has ballooned up to do way more than just sell music, and in Doubletwist it's much more straightforward. Here's the other bonus for Mac users: while we originally had to wait for an app release, the music store is currently only available on the Mac version of the software. A PC version is coming soon.

It's doubtful Doubletwist will replace iTunes for many people, given all of the various things iTunes does for a Mac user. But then again, if you are using the Amazon MP3 store with any frequency, Doubletwist is probably worth a look: it's a free download on the website.