I wonder if it's possible to use the SIM in another phone (assuming there is a SIM).

For these prices, it would pay to get the phone for the SIM alone...

Virgin Mobile runs on the Sprint network (CDMA) so no sim card. However, I believe the Optimus V can easily be setup to be a wifi hotspot and share your "unlimited" data.

I wish one of the GSM providers would do a similar option to use in my N900.