3d Games for Architectural Walk-through's

Digital Urban has an article with 2 proof-of-concept videos showing architectural models which have been imported in the Crysis game engine.

This is an intriguing prospect. Imagine yourself leading your client on a tour of your urban design. Any number of clients (who are sitting at their computers) can follow along with you and hear your voice, look around, and share the experience. They can also go exploring on their own at their leasure.

Modern games are powerful. They support real-time shadows and ambient sounds. It would be a powerful selling tool.

The workflow used in the videos was SketchUp -> 3d Max -> Crysis.

Does anyone have any experience with this and are there freely available tools for trying this?

(article)