The PS3 has its hardware upscaler that most developers simply dont use or are learning to use right now.
I would say most of the more recent games have 1080i support through that upscaler.At least thats the impression I got from the last Eurogamer round ups.
Sonys policy seems to be right now giving support to the 1080i machines but for the 1080p upscaling let your HDTV do the work.It has some sense ,as if you have a FULL HD TV to effectively enjoy the 1080p display the truth is that the HDTV makes itself the upgrading so why bother?







