CONCLUSION
While we can't definitively name one console as having better multi-platform releases across the board, there's a clear winner among these four games: PlayStation 3 beats the Xbox 360 handily. Call of Duty 4 plays nearly the same on both systems, differing only in superior online integration on PlayStation 3. With Devil May Cry 4, the game is all-around better on PlayStation 3 (despite the horrendous installation process). Burnout Paradise emerges as decidedly better on Sony's system thanks to EA Criterion's decision to make it the leading version of the game. The exact opposite is true for Assassin's Creed where Xbox 360 beats out its PlayStation 3 counterpart visually.
Judging by what we've seen with these recent games, you may be better off picking up PlayStation 3 versions of high-profile multi-platform games for the time being. The notion that PlayStation 3 ports are inherently inferior to Xbox 360 simply doesn't hold water these days. Some games do perform worse on Sony's console--Blacksite: Area 51 has been plagued with performance issues, for instance, and The Orange Box suffers from groan-inducing load times and chugging framerates.
These issues are slowly being addressed, though, as many publishers are starting to churn out multi-platform releases with an eye for the PlayStation 3. LucasArts recently announced an initiative to make the PS3 their leading platform for development, joining a growing wave of developers seeking to improve multi-platform games heading to Sony's console. With any luck, this movement will result in better performance for all gamers, Xbox 360 and PS3 alike. For now though, just enjoy fragging terrorists, crashing cars, and slicing demons in half on your PlayStation 3.
OVERALL EDGE: PlayStation 3
rologue and 5, but I got this game with it and decided to give it a test run for a while and am pretty impressed though I havent gotten far.
Nice find Rhino. 
