PageRank is a link analysis algorithm that assigns a numerical weighting to each element of a hyperlinked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set. The algorithm may be applied to any collection of entities with reciprocal quotations and references. The numerical weight that it assigns to any given element E is also called the PageRank of E and denoted by PR(E).
Here's another explanation about page rank and how to make the most of it.
I'm not sure how often does Google update their Page Rank. I just found out that my new blog, Anak ni Edring, which I started last month has now a PR3! However, my other blog, Canada Visa Application Online Resource, which is older and more active has got only a PR2 until now. Weird.
Anyway, if you want to check what your page rank is, visit www.prchecker.info