New PageRank: a reverse Sandbox?

This blog is barely two months old and its homepage has been assigned a Google toolbar PR of 5. It sure is heart warming to see the little green bar fill up. But will it last? In my experience definitely not. The assigned value is not only too high, I’ve also seen this happen to one of our other sites. That site reached an inexplicable PR 6, which lasted for about two months, before dropping back to a more middle of the road 4.

How can this temporary PR phenomenon be explained? Well, the crystal ball is out of service again, so I’ll have to guess. My assumption is that the algo “guesses” the PR a promising site may attain in the future. But when the links don’t materialise, the toolbar PR shows it’s true colours, after some months. Call it a reverse sandbox.

Someone mentioned that in some cases pages that aren’t even indexed yet show some green. Could Google be extrapolating from other, indexed pages from the same domain?