RegMyUDiD or AA could write a warning at there sites, that this method doesn't work as soon as apple fixed this problem...but they want the stupid buyers to buy the more expensive cert instead.
This is why I posted this
A friend of mine has this problem since the beta 1...
It's not possible to get the mobileprovision from the dev center - it's the apple dev center and not the iOS beta.
Off-topic, I love your avatar
But basically on-topic what urhacked said.