Why are my games always playing at 720p resolution, not 1080p?

I got an Aquos full HD LCD, but the resolution is always 720p while playing the PS3, never 1080p. Can anybody tell me why it's like that and how to change it into 1080p if possible? Oh, but GT5 plays at 1080p, which confuses me more. Thanks for the help!

PS3 video setting, check 1080P

You have to look on the back of the box of the game, some PS3 games wont upscale so they will only play at 720p. Come to think of it I think most of my Ps3 games only play at 720p.

Almost every game is native 720p, or a little lower or higher. There's a list of like 12 games that are native 1080p on the xbox, and they have low quality textures and stuff to compensate. The consoles just can't handle it. Maybe next gen. Or you could build a gaming PC.