Pocketnow, via a wireless accessories website, has apparently discovered the names of 3 of the carrier-branded versions of the Galaxy S II that will be coming stateside later this year. The device will be known as the Attain on AT&T, the Function on Verizon Wireless, and the Within on Sprint.
Mysteriously absent is a T-Mobile version, suggesting either that the device won't be coming to America's pinkest carrier, or that it will be arriving in a different (QWERTY?) form-factor which does not fit the case being advertised on the source webpage. Either that, or they just don't know the name of it, yet.
This all, technically speaking, a rumor - so take it with a grain of salt. At the same time, these names sound pretty legit, so, this could be the real deal.