Last night we saw Sony's clamshell S2 tablet get the once-over from the FCC, and this morning the S1 and its more traditional tablet form factor has gotten the same treatment. There are actually several versions of the S1 that appeared in the FCC: the SGPT111US/SGPT112US feature only WiFi connectivity, while the SGPT113JP/SGPT114JP pack WiFi as well as support for WCDMA bands II and V, which happen to be the 850/1900MHz bands that AT&T uses for its 3G network.
The last to letters of each model of the S1 suggests that the U.S. will be getting a WiFi-only version of the device while Japan will see a 3G-enabled model, but that doesn't mean that an S1 with a cellular radio won't make an appearance stateside at some point in the future. After all, if the S2 is coming with AT&T 3G, why not the S1 as well? We'll keep you updated.