This is my video of the mobile virtualization demo from VMworld Europe 2009.
This is the device that was demoed: http://www.nokiausa.com/find-products/phones/nokia-n800-r6. While this is not a phone like what is mentioned in the video it is still very impressive. There are hurdles to take though because you will probably want to have different phone numbers attached to different environments and that usually means multiple SIM cards (in the case of GSM).