aristotle - 4:55 pm on Mar 5, 2010 (gmt 0)
The internet is growing at a rapid rate. Millions of new pages are created everyday just on social networking sites alone. This is one reason Google decided to implement Caffeine, to increase their data handling capacity to keep up with the growth. But Caffeine hasn't been implemented yet, and in the meantime Google may have to drop some pages from the index in order to make room for new pages.