I use about 4-5 computers between all the places I am at. I have always wanted to have my folders in sync between the machines to get a unified view of the way data my data and files are organized. There are many tools like I have tried (E. g.Sync Toys from Microsoft), but they are very limited.
While I have Goole Desktop on one of my computers (not the new version), I do not have it configured to not send any data back to google and have a few firewalls to verify internet activity, though it is hard at time to guess.
While searching across computers using the technique proposed by Google, works. I would think that it is technically the least feasible. I would better install some peer-to-peer software that exchanges meta data between the known peers and keep the files in sync. If you have Cygwin, even rsync could do the job with a little workaround with your NAT routers.
However the approach taken by Google will require tremendous amount of storage capacity and and other networking and computing resources to enable cross computer searching. Now given that the tool is “free”, why would a for profit company want to take this approach? Bear in mind that they have some of the brightest minds working for them, so lack of technical competence is ruled out.
My take is, better information all all aspects of a person using their services.
Well they can index everything from your surfing habits to your personal documents. Then they can mine the data that can be very (did I say very) valuable for marketers and targeted advertisers. But with so much data on a indivisual, it is like the apple in the Garden of Eden, too hard to resist the temptation. No matter what Google says about privacy, it is not something I would do and will proactively advocate other people not to use it.