Its 99.99999% sure, ive been told by somebody that it was in the official xbox mag but also seen it in two other mags myself, one showing all the xbox live games to be released in the next few months and PES4 is one of them!
Trust me it is happening, i think konami have confirmed it somewhere, i posted a bit more detail in the first few pages of this thread
Also i doubt we will see PES4 on PS2, its too late, their online play isnt as good as xobx live and i think that xbox live being pushed back its release date to november gives them loads of time to build in online play