I'm definitely seeing PR fluctuate right now. Take a look at WordPress.com, it's coming up as Unranked.
Yeah, Google is either heavily penalizing certain types of sites or they aren't showing full PR results. Either way, I've had at least one domain go from 0 to 2 so there is definitely an update going on as we speak.
Looks like an update incoming... My PR7 home page is gray barred at the moment, yet still ranking in same positions for all of my major keywords that I checked. Yet my level 2 pages on the same site are showing a PR6 as is normal.
Yeah, I'm seeing similar results on my primary domain. My homepage is showing as unranked (down from a PR6), but an internal page went from PR 3 to PR 6. Using http://www.digpagerank.com to check my PR, it shows that many of Google's Data Center's are down.