HSDPA phones don't get any slimmer than this. Measuring in at a scant 8.9mm thick, the Samsung A727 (shown) might be the thinnest HSDPA-enabled cellphone around. AT&T managed to nab the A727 along with its 12.9mm-thick brother, the A717l.
Both phones make Nokia's 6120 (another slim HSDPA phone) seem like a whopper by comparison. They also feature a microSD slot and built-in camera. I just hope their battery life isn't as thin as their waistline.
AT&T Gets Slim Samsung A727 and A717 [Phone Arena]