Monsieur - theyve been doing the Page Rank updates randomly -
Here's a small list:
Google toolbar Page Rank update / time since previous update
April 22, 2005 / 111 days
January 1, 2005 / 87 days
October 6, 2004 /106 days
June 22, 2004 / 22 days
May 31, 2004 / 38 days
April 23, 2004 / 16 days
April 7, 2004 / 22 days
March 16, 2004 / 50 days
January 26, 2004 / 15 days
December 23, 2003 / 17 days
December 6, 2003 / 20 days
The other important factor in this is this is just when they update the toolbar PR numbers - not the actual Page Ranks
The Google Directory has a much better history of being almost monthly for its PR indicator updates - remember that the Directory indicator is 8 places compared to the toolbar which is based on 10.
As far as the toolbar PR being useless/BS - this was just my opinion based on the fact that Google has stated that the backlinks indicator in the toolbar has been scrambled on purpose (happened due to a SEO recommending it to Googles rep at a SEO show back in early 2004)- and the site: command has been changed recently to not include the site scrapers and hijackers 302 redirects (this was Googles response to many complaints about scrapers and 302s). This leads me to believe that Google has also scrambled the code for the toolbar PR to give people trying to SEO more confusion - as well as the fact that the PR indicated can be manipulated by anyone with a little savvy - if you wanted a page to show PR10 on the toolbar you could do it within 2 days with no problem (of course it would be stupid to show ya'll how)
The main part of the toolbar PR being BS is that the numbers they are showing, just like the backlinks, dont match pages in the directory which has always been a much better relative ranking and PR indicator and closely matches the SERP rankings where the real Page Rank is taken into account.
I believe in an old article I wrote for Adult Buzz or one of the other web pubs I had stated that over 100 factors on and off page really go into the "actual" Page Rank - based on the Google founders original page rank paper and testing that we did to try to rank the importance of the factors - these factors are still just as important and far outweigh the indicated PR on the toolbar which brought me to my conclusion that using the little green bar is useless - add to that Google's neverending attempts to mislead SEOs trying to game them (which they are very good at and have engineers that do nothing but these types of projects) I would say that looking at the actual high ranking pages and studying why they rank so high (the real Page Rank effects) is a much better use of time
Sorry - too much coffee this morning