Personally, I wouldn't move to work for a big company like Google after running a successful startup like this unless I had to as part of the deal. Not because Google is evil, but because you lose your independence. I wonder if that was part of the deal.
Isn't that part of getting acquired? You typically don't get acquired by other startups (they don't have money), and you typically get far less of a payout if you don't work for the acquirer afterwards (they want the talent that built the software in addition to the software itself).
