If you’re the type of person who likes to make prank calls, the “Truth in Caller ID Act of 2010” bill that was just passed won’t be something you’ll like. Under said bill, it will become illegal to use any caller ID service to transmit misleading or inaccurate caller ID information, with intent to defraud and deceive. And this change will affect any real time voice communications service, which includes VoIP. That being said, you’re still able to block your own outgoing caller ID information, and law enforcement isn’t affected as well. This is certainly good for safety purposes, but folks will need to figure out another way to play pranks on folks.
PDF link to said bill.