Spaceharfang can answer in more detail, as he's the brains behind this work, but I believe this is an intermediate step. For now, both "top collectors" and "rank" are at last using the same heuristic to compute uberness. This is not the end! Spaceharfang is setting things up such that a variety of ranks (completion, volume, bargain-level, value, and figure count have all been suggested) can be generated with the same ease, and I believe that once we have a bunch of them we'll find some way to mix them all together to create a composite number, which will become The Rank. I think what we'll do is show all the ranks on your profile page, so it's more clear what's happening.
With this work, Spaceharfang says we'll also finally be able to browse users by rank. Yay, I say!
