So many sites can expect their pagerank to decrease (as a result of the additional pages, with no direct influence on the ranking).
I don't think anything will be reflected in this. They didn't just push a button and whoila, now were at 4.3 billion. They simply updated the text on their home page. Keep in mind they have been counting the pages since November '02. I wonder if that was the project GoogleGuy was working on. 4,285,199,772 4,285,199,773 4,285,199,774 Done! Notice how he's been posting more lately.;)
<added>When I started typing the above, GG's post wasn't there. Coincidence? Not with all these black spaceships hovering outside.;)</added>