Looks like pdxusa has won this round...
[urlhttp://arstechnica.com/tech-policy/news/2010/04/congress-outlaws-all-caller-id-spoofing-voip-too.ars]Congress outlaws all Caller ID spoofing (VoIP too)[/url]
The House has passed the "Truth in Caller ID Act of 2010" (PDF), which does exactly what its name would lead you to believe.
Under the bill, it becomes illegal "to cause any caller ID service to transmit misleading or inaccurate caller ID information, with the intent to defraud or deceive." The bill maintains an exemption for blocking one's own outgoing caller ID information, and law enforcement isn't affected.
The change will affect "any real time voice communications service, regardless of the technology or network utilized," so VoIP calls are included. In fact, the Congressional Research Service summary of the initial text makes clear that VoIP was a key target here.
The Senate has already passed its version of the bill back in February, so it should be signed into law soon.
CTIA - The Wireless Association said today that it supports "making caller identification spoofing illegal as the applications of such an activity are usually for malicious purposes."