Everyone's gotta pay the bills. If you're thrifty, 4-5 years at a company like Google can get you .5-1 mil for your next venture (maybe more, maybe less, depending on your bonuses & promotions, how well the stock performs, etc.)

I wouldn't expect any meaningful new product or anything to come out of this - if I had to guess, he was probably hired as an IC. Don't expect him to become some sort of new figurehead at Google for anonymity or identity on the Internet.

Have fun Chris.