they have one for each carrier's version. delivered in 2 days.
I really like my Diztronic Matte Black case from Amazon. (Bonus: Verizon model.) It has a great feel compared to the somewhat slimy back of the G2.
Personally, I love the form factor of a G2 without the case... I just have been using one because I can't stand having a Samsung-like plastic on the back of a phone. I will most likely skin my phone soon.