Just one day after the launch of the first Android-based phone in the US, official G1 carrier T-Mobile USA has already started pushing out updates.

The official T-Mobile forums for the G1 have been a hive of activity this week, not least because of the revelation of a new software update which was made available on Thursday.

No one appears to have a definitive answer about what is included in the update, which upgrades the initial Release Candidate version from RC19 to RC28, even the T-Mobile engineers themselves have given vague answers, but most of the update seems to concern bug fixes for the Amazon music application.

The G1, built by HTC, comes preloaded with Amazon MP3, allowing users to search, download, buy and play music from a catalogue of over 6 million DRM-free tracks.

Downloading music from Amazon MP3 on Android requires a wifi connection but searching, browsing, listening to samples and buying MP3s can be done over cellular. Tracks can be managed by any music library software and transferred between and played on different devices.

Releasing an update so soon may bode well for the platform, and increase its competitiveness if the Open Handset Alliance is seeking to address bugs as they arise.

According to T-Mobile, customers who participated in the presale should receive it between October 23 and 25, otherwise they should get it by October 31. Devices bought from November will have the update pre-installed.