The FCC isn’t coming out and telling us exactly what the above device is, but as the boys at Engadget have noted, a T-Mobile friendly version of the HTC One S just passed through the FCC. This particular model comes equipped with a AWS 3G radio in addition to 850/1900 bands. There is some speculation that the PJ58100 is the One S for T-Mobile, not the device seen above, the PJ40100. The PJ58100 passed through the FCC around two weeks ago and the two devices differ in the location of the WLAN / BT antenna.
Current intel points to an April launch for the HTC One S and we hope that passing the FCC is one of the last hurdles before launch.