I mentioned capped EU data during a conversation I was having with T-Mobile recently and apparently it is
coming (most likely due to an EU mandate) but there's no certainty as to when. Probably in early 2009.
However, I think the guy confirmed that data would be £3.50 per megabyte (out of allowance) in Germany when I go over there in October - I'll still disable my data connection, but I balked slightly at the fact that when you're theoretically roaming in T-Mobile's home network, you still get charged roaming fees! Orange sorted this out years ago, if you roam to another Orange network it's counted as your home network. Why can't the other networks at least sort this out amongst their various branches across the EU