720p is 1280x720 at progressive scan, period. 1366x768 is typically called 768p or WXGA.
It's true that TVs with a resolution of WXGA are often called something similar
LG 26LD350 26" LD350 Series 720p LCD HDTV
The 720p here has nothing to do with the resolution, it only means that the TV is ready to play typical HD content (which is broadcast in 1080i or 720p modes).