Here's the scoop... you can view your page with the PageRank identified for each link on that page. VERY handy, to say the least! A massive time-saver for those of you concerned about PageRank, Lisa suggests checking your SiteMap to get quick PRs.
Not sure who's offering the tool, as it isn't branded in any shape or form. I suspect it's coming and the handy tool is a bit of a link building strategy (ahem, read Link Bait). But that's OK with me, as it's a gem and I hope it stays!