T-Mobile has officially released the G1 handset, the first smartphone based on Google's open source Android platform.

The G1 made its debut on 22 October at T-Mobile stores in the US. While the release lacked the hype and media attention of the first two iPhone releases, the G1 is expected to be Apple's strongest challenger.

Both devices feature touch screens, 3G connections and support for third-party applications.

Google hopes that the Android platform will differentiate itself from the iPhone by offering a completely open marketplace in contrast to Apple's tightly controlled iPhone AppStore.

The Android Market went live today to coincide with the T-Mobile G1 release, featuring an initial 50 previously submitted applications.

Google hopes to expand its application line-up on 27 October when the store will open for submissions from third-party developers.

The company plans to allow developers to choose whether to give the apps away for free or charge a purchase price, of which Google will keep 30 per cent. Apple charges an identical commission on the sale of iPhone apps.

The release of the G1 and Android Market come just one day after Google released the Android code base under an open source licence. The company hopes that the move will further lure developers to the platform.

T-Mobile is expected to release the G1 in the UK in November.