For those that still worry or look at page rank - Google has updated today. To be honest I think that once a website has a PR1 then that's as far as the analysis needs to be. It really doesn't matter after that. IMO
The last TBPR update was on November 7 [webmasterworld.com]. Sometimes there is a kind of flux that follows after a PR export - but this would be extremely quick for a full TBPR export. Normally it's about every three months, and it's been as long as six months between updates.
We did see some rapid PR changes earlier this year, on Jun27 - Jul 18 - Aug 5, apparently working out some bugs. The Nov 7 update did seem a bit buggy to me, but that's often the case, and I'm not seeing any changes or hearing any buzz about it.