Alright, folks -- if you've already got a T-Mobile UK account in your back pocket, you can breathe a sigh of relief, because that ugly new data cap doesn't apply to you. It took the operator just a day to realize that putting a hazy "fair use" restriction of just 500MB per month on existing accounts wasn't going over too well with its customer base, so they've conducted a "further review" and decided that they'll instead only be applying the rule to new and upgrading customers as of February 1 only. We wouldn't call this an outright win by any stretch -- the policy is still enormously restrictive, vague, and a pretty clear-cut disadvantage of the competition-reducing Everything Everywhere hookup, and it looks like they'll still end up tagging you as soon as you try to upgrade your plan or your hardware anyway... but we'll take whatever reprieve we can get.
[Thanks to everyone who sent this in]