Google just recently released the Android 1.5 "Cupcake" SDK to developers, but several intrepid coders from the XDA-Developer community have been working with the G1. An individual known as haykuro has successfully ported the software from the upcoming HTC Magic to the G1.
According to the developers, there is extensive amounts of work required to get the software ported over, but it isn't anything that an average developer or user would be unable to do. There are numerous tutorials thanks to the XDA commuinty.
The upcoming release of Android 1.5 "Cupcake" has been highly anticipated. There will be numerous new features and additions to the software. With T-Mobile's April 21's launch event, many are anticipating the release of Cupcake to the public.
[Via Boy Genius Report]