There's a great 2D Flash version of Mirror's Edge over at Borne Games. You can immediately play through the beta at that link and offer any feedback to the developers. The full flash version will apparently be free.
This first level (surprisingly long) is fluid and fun, though I wonder why the developers chose the "S" and "/" keys for jumping, rather than the Spacebar, which seems more standard and is certainly more natural to me.
Publishers are definitely experimenting a lot these days with internet marketing. This Flash game does a great job of mimicking the Mirror Edge experience I had in the Xbox Live demo. The game encourages replay to try for the fastest, smoothest possible run. It's about momentum, and few games are.
I'm undecided on the 360 version of Mirror's Edge. Because the demo is only a training level, the experience is broken up. I can only guess that further levels have fewer story pauses and are more open to individual choices. The longer it lets me run, jump, and slide in one continuous experience, the more I enjoy it.