When does google PR update?
 

Beginning of the month usually the same as when the listings change? I have no clue.. We have a bunch of PR0 pages I'm hoping will be erm, activated.. :)

google is in the middle of this months update. check out www2 and www3 to see how you rank. you won't be able to find out the PR until the update is complete and the www2 + 3 db are tranfered over to the main www

Is the PR 0 a gray and blank PR or a white and black PR?

There is a difference.

Gray means that the page is not indexed
White means that the page is penalized (for some sort of SE spamming)

And ryph is right, your true PR won't show through until the dance is over.