Yes here's some info...
Playable Demos
Mortal Kombat: Shaolin Monks
Rainbow Six: Lockdown (Live Enabled)
Hulk Ultimate Destruction
There's also videos of Far Cry Instincts, Call of Duty 2 (X360), Burnout Revenge, The Suffering: Ties That Bind, Ultimate Spider-Man and more.
If you're wondering about the Lockdown demo, I don't like it too much. It's not bad but I don't really like it either. No matter what gun I choose in my profile I start with an MP5 for some reason. And then the mode is some really annoying gametype where each team has to steal these canisters...And it's kind of confusing.
Honestly, I'm more impressed with Mortal Kombat: Shaolin Monks which is the best thing I've played from Midway in quite some time. The cut-scenes and voice acting suck, but the actual gameplay is deep and really fun.