Although UbiSoft is not confirming the worst kept secret in videogaming, Computers and Videogames came out with an Assassin's Creed Preview...for the Xbox 360. They also branded it with the Official Xbox Magazine logo, meaning it will probably be in the next issue of OXM. Of course, Ubi isn't saying whether it is true or not, but honestly this is the worst kept secret in gaming.
"PS3 only" were the words floating around Assassin's Creed at E3 (although no one announced exclusivity to the PS3, it is just that only the PS3 was named for the game). The game was previously shown at X05 (a Microsoft event) as Project Assassin. Several sites, whether true or not, say that the game was shown at E3 on an Xbox 360 with a sheet over it, hiding the fact it was running off of that and not a PS3 prototype. In the end the fact is that Assassin's Creed will most likely come to the 360, whether it be the same day as the PS3 version or after a timed exclusivity agreement. This kind of thing made me think about another game that may teeter on the multiplatform edge considering the amount of bad press Sony is getting and the general unexcited attitude of many developers about the system.
That game is the 3rd party crown jewel for Sony and the PS3: Metal Gear Solid 4: Guns of the Patriots.
You guys are probably thinking I'm crazy, but this could possibly happen. Kojima said MGS4 was PS3 only at the "current time" in June 2005 and that he had no plans to port it. However, his tune may change given how news of the PS3 has hit here in North America and Europe, the two countries where the MGS series sells very well versus the Japanese market. Given the fact that this game probably won't see release until the latter half of 2007, Kojima and Konami could find that the Xbox 360 has a stranglehold on overall system numbers everywhere outside of Japan. They may release it PS3 only in Japan and release it multi-platform here, possibly giving the PS3 version a more special treatment...or they could make a 360 version as the base system from where to make the PS3 version.
I don't know if the 360 will ever put a dent into Japan, but if enough of the Japanese developed 360 only games are of high quality they may start to make headway. I'm not saying MGS4 will be coming out on 360, but who really knows. I think Sony has created its own possible catastrophe everywhere outside of Japan (and possibly in Japan to when put up against the Wii).