I think alot of that list are just PS2 games being ported to 360. Porting from PS2 to 360 albeit not ideal is very doable, but doing so to the PS3 isn't probably worth the effort. It's a completely different kettle of fish to comapring a 360 game to PS3 port or whatever.
Also with that list, alot of those games take me as random 'scraps' of E3 lists which then never exsisted, got canned etc.
But yeah, we really don't have any true source on porting costs. I work part-time in the gaming press and have got to chat to a few PR's, developers etc. From what I picked up 10% used to be the porting estimated figure but since then it's dropped as engines are refined and game developement caters for both consoles from the off. I've no doubt there are examples where it's turned out much higher and much lower though.
The Assassin's Creed lead tech guy person said it cost less then 10% to port, but I can't for the life of me find the link to the interview. That's about the only internet source I can find on any estimate of the costs.
But yeah, no one's going to ignore the PS3 if they want to maximise profits...