According to Betanews, T-Mobile USA’s Erica Gordon denied that the company had any plans for a Cupcake related firmware update for the T-Mobile G1 in April, which is what Pocket-link.com quoted an unnamed source at T-Mobile UK as saying.
Gordon told Betanews that it was “just a rumor” and that she was not aware of T-Mobile International having any such plans. It is worth noting, however, that she does not actually represent T-Mobile in any countries outside of the USA.
In the past, though, the UK and other countries have always received new firmware updates a week or two after the USA. Considering U.S. based Google’s involvement in the G1’s development, it would not be a surprise if T-Mobile USA had the lead for development when it comes to T-Mobile’s various international units.