No Twitter for T-Mobile users? It's working for me!

I've been reading today that T-Mobile apparently cut off access to twitter by its users.. I don't get it! I just sent a message to Twitter via my mobile device using txt messaging enabled via Twitter and it works just fine! Mindyou, I have an unlocked device that I use so perhaps that's the issue! I guess if T-mobile users really can't send to twitter they could use a third party app like Twibble - see also the Twitter blog