That's tricky. They may have both. But that's a good question to survey the August 2006 CBT's and January 2007 CBT's.
TP testing centers don't just administer the MCAT, DAT, GRE, or GMAT, but also have a ton of other exams. I would hesitate to think that each test will have its own little rules about handing out paper only, dry-erase pages, or what. All I do know is that TP centers started going to dry-erase pages for the GMAT last year over scratch paper.