The Resident Evil 5 demo that was previously available in Japan will be available in the US during the week of January 26th. It will be "premiering exclusively on Xbox 360."
Keep in mind, this does not mean the demo itself is exclusive to the Xbox 360, as PS3 gamers will get the demo at some point. It's also possible that Microsoft is claiming the exclusive premiere because in many cases, it publishes new content before Sony. Sony, as you know, only publishes new content on Thursdays...or it could be a week or two between the Xbox 360 and PS3 versions. We'll see.
For a refresh of what you'll get to play, here's our footage from the Japanese demo: