I've got it; I was at Google about a year back when they had an open beta. At that time they were encouraging everyone at the company who'd signed up to take home the beta client and install it on whatever computers they wished. It works okay; There's a bug where it will occasionally re-sync everything, but last I saw there was serious work on it.

Why haven't they released it, if it was this close to finished? I can't say. Likely bad allocation of resources and decisions by product people. Larry is chasing Wall Street targets, which has badly slowed the pace of innovation in most of the company. The moonshots are sacred and given free reign, everyone else isn't allowed to innovate.