According to the Computer World article.
The broadband and VOIP providers had to send the FCC by March 12 a plan to comply with CALEA, and by Monday they had to either set up a system that allows monitoring or hire an outside company to make it possible. Those that don't comply must make a good-faith effort to do so and may be referred for enforcement.
This requirement is a little ambiguous, in Vonage's case - they would need to provide wiretap capabilities for both OnNet and OffNet calls without question - in both cases someone is calling a phone number (even if it is redirected to a SIP URI), however Skype operates a little different than a traditional ITSP - in Skype's case would they be forced to provide a method of 'listening' for calls that are on the P2P network? Wiretapping a call that terminates to the PSTN via a SIP gateway wouldn't be that difficult; but Skype has publicly said in the past that all traffic on the P2P is encrypted and even they cannot listen in on calls or messages the way the system is set up.
So will the FCC force them to open up a method to do so, if they don't comply voluntarily? Or are P2P calls not subject to the same wiretap rules? It seems to be a bit of a grey area.