Microsoft said that a Surface 2 with LTE was coming to ATT early this year, and it now appears that this cellular-equipped Windows RT tablet is finally close to launch. The company has just received FCC approval for a portable computing device that sports the Surfaces familiar 10.6-inch display as well as ATT-native LTE and HSPA data. The filing doesnt hold any surprises, then, but it suggests that there are few obstacles left to releasing the 4G slate in the US.