I messed with Cedega and it was a pain to get each game working. It's cool, but still has a long way to go.
From what I read, this is a virtual system and you can load any windows OS inside Linux. That in itself isn't that interesting. What is interesting is you can access individual apps as if they were running in linux. So, instead of switching to the windows os, you can actually run IE on top of your linux desktop or any other app for that matter. It's kind of a perception trick, but it's cool and it gives you full windows API access instead of emulation.
I think it's a great idea. I may try it out on my second system.
The problem I have had with VMs is that they tend to have to use base drivers for base components, thus your video card will be a nvidia 5500 instead of 8800GT
Ah, that would make more sense why Cedega is so important. It probably allows better driver interaction.