LG GW520 and LG Callisto, the LG GW525 has been approved by the FCC (as GW525g) and since it features 850/1900 GSM and WCDMA connectivity, it's theoretically ready for AT&T's network. Still, we have no info about a possible LG GW525 release on AT&T, so this might never happen.
However, we've heard that the GW525g will be launched in Latin America -- Argentina and Chile -- but we don't know when exactly.
LG GW520 / GW525 / GW525g is a touchscreen phone with a 240 x 400 pixels display, sliding QWERTY keyboard, push email, document viewer, threaded SMS, Bluetooth, MP3 & MP4 player, 3.15 Megapixel camera, 40MB of memory and microSD card slot.