"These numbers are all crazily low," Farach-Colton [Martin Farach-Colton, a professor of computer science at Rutgers University] continued. "Google always reports much, much lower numbers than are true."
Whenever somebody from Google puts together a new presentation, he explained, the PR department vets the talk and hacks down the numbers.
The interesting angle here is that, as opposed to blowing their own horn as loudly as possible, Google apparently feels a need to soft pedal their status, and not make themselves into an overly large target.
Of course, they already are a large target (just look at the last few weeks) but apparently they've been turning the knob down for quite a while.