How do you see that you are using data and not voice? When i place a call to another skype user, my phone dials a number - this is clearly a voice call. Maybe vzw has some magic accounting that will not count those calls towards your monthly allowance, but it is still a voice call from the phone.
The details have been talked about on several web sites for the last few days, like
here on driodlife. Skype to Skype calls use Verizon's 3G network and are free under your unlimited data plan. Skype to land line or mobile phone calls go over Verizon's voice network and use your plan minutes and, I believe, also your Skype credit.
The fact that it can't be used over wifi was stated in Verizon's original announcement in mid February, so I don't know why that's a surprise for everybody.