Bugger..General comments on the net suggest T-Mobile is the front runner.. AT&T have the American contract and it seems that T-Mobile could be the logical choice..
However there are questions about thier ability - seeming that they are a much smaller provider than Vodaphone..
T-Mobile to secure iPhone distribution rights in Europe? at Pocket Picks
T-Mobile ahead on iPhone deal - iPod/iTunes - Macworld UK
Tech Digest: T-Mobile is European frontrunner for exclusive iPhone deal, sources claim
5/2 on T-Mobile..?