goodroi - 1:25 pm on Aug 9, 2005 (gmt 0)
The engines have never kept the size of their index up to date. Recently Yahoo updated that their index is 19.2 billion documents. Yahoo also made a good point
I would guess that Google's index is bit larger than 8 billion but that it doesn't really matter much.
size is only one dimension of the quality of a search engine