The Android software platform, which is Google’s big mobile bet, inched a step closer to commercial reality on Monday, as developers unveiled a beta SDK.

The Open Handset Alliance, which is tasked with developing the platform, has lifted the curtain on Android 0.9 SDK beta, which should give some indication of the commercial readiness of the platform.

The first Android devices are expected to hit the shelves in the fourth quarter, and the OHA said “The APIs are now pretty stable and we don’t expect any major changes,” between 0.9 and version 1.0 which will ship on retail handsets.

The OHA said the new beta features a lot of changes, including a new home screen, which means the finished version will probably look very different to the software emulations and early versions we’ve seen so far.

HTC’s forthcoming Dream handset, which looks set to be the first commercial device to ship with Android, has also been approved for use in the US by the FCC. Documentation submitted by HTC to the regulator asks for confidentially on some of the details until November 10, which may point to the gadget’s launch date.

T-Mobile USA is expected to offer the device, but the Dream’s operating frequencies of 850MHz and 1900MHz WCDMA mean it could be used on AT&T’s network as well.