Page Rank Question
 

Why would site http://blah.com be a page rank of 0
and the same site with www. http://www.blah.com be a 4?

Because sites linking to you would link to http://www.blah.com instead of http://blah.com.

most likely because www.blah.com has links to it from major sites, like Yahoo, while blah.com does not.

Obviiously www.blah.com and blah.com are treated differently.

...because www. is treated like any other subdomain would.
XM