mfagan : You should also search on the first statement of Gary price :
1) On our recent post about Google size estimates being off, a Google spokesperson tells us what we for the most part already knew, "We looked at your queries and the bottom line is that Google's estimator is an estimate, not an exact number...we're working to making it more accurate." Like I said a few days ago, those of you who use Google page estimates as a way of determining popularity need to be very careful.
This was his recent post [resourceshelf.com] and check the Exemple 2!
But he did not investigate deeply enough like I post it here [webmasterworld.com] with no answer at all.