The New York Times (registration required) has an article this morning on the FCC's decision to require VoIP service providers to implement phonetapping equipment. There will be public hearings before a final decision is made, but if the Federal government proceeds with this, it will burden the nascent industry with large costs and it will be mostly for naught.
Wiretapping a Voice over IP phone requires much more sophisticated equipment than the legacy phone system, and indeed, the term "wiretapping" hardly makes sense, since with VoIP you tap packets, not a physical wire connection. Those costs will be passed directly to consumers, increasing the cost of VoIP services and slowing the potential cost savings to consumers and businesses.
If VoIP tapping is implemented, bad guys won't use it. They will, instead, use any of a myriad of point to point voice conferencing software packages that are already in wide use. It's a little less convenient, but beyond the control of the government to stop. Outlaw such software (very unlikely), and bootleg software to do that will quickly become an illegal business opportunity.
Like so many businesses and governments, the FBI and other Federal agencies have failed to adapt to a changing environment. One can only hope that the public hearings bring this out and save us from the expense, waste, and lost business opportunities.