According to a statement from T-Mobile, the RC33 update is on the way to the G1 soon. But this is not the Cupcake that everyone has been waiting for. Looks like just a few little bugfixes and a few new features:
“To ensure a great experience with the T-Mobile G1 with Google, customers with these devices will receive an Over the Air (OTA) update to their devices between February 5 and February 15. This OTA will include new system enhancements such as the ability to save pictures or files to file by long-pressing an item, check for system updates, and use the Google Voice Search feature. The OTA will also fix a number of known issues. New G1 activations will receive the OTA up to three days after service has been activated.”

