PPMC = Podling Project Management Committee: the current committers IPMC = Incubator PMC. Includes our Mentors PMC = Once we graduate, some chosen subset of the committers and contributors become the PMC.
After doing some digging I finally found this document http://incubator.apache.org/guides/releasemanagement.html that states that while we are in *incubation*, the PPMC members DO NOT vote on a release. It must be IPMC members, which includes our Mentors. And to get the release accepted, we need at least 3 IPMC members to vote with a [+1]. Since we only have 3 Mentors, all three of them must vote with a [+1].
