Seamlessly integrated Windows apps running on Mac

I’ve been trying out the beta of VMware Fusion on my Mac Pro. It’s exceptionally impressive. In Unity mode you can run Windows applications within OS X, and they just appear like other OS X applications. You don’t see the Windows desktop or anything, and they are treated just like Mac applications by Expose and everything else. I don’t have much need for Windows applications but it’s nice to have the option of using Internet Explorer or Windows Media Player occasionally, and to have them running in such a simple and non-intrusive way on my Mac is wonderful.