Every time you add a picture to your gmail contact's profile, you are asked to crop it to seperate the face from the body. So Google has, somewhere, a huge database with people's headshots tied with nicknames and other information. I wonder why...
Now hear this: Google was very close in acquiring Riya, a face recognition service which expanded into a visual search engine. The deal broke since Google decided to develop an in-house solution. This prooves their intentions in developing algorithms for processing and recognizing faces.
How about that? You enter google.com, search a name/nickname and download the guy's/gal's photo. Another scenario describes you taking a photo with your digital camera/cell phone, uploading it to the search engine and identify the displayed person. OMG. This is just huge. What's next? License plate identification?
Of course there are serious legal implications mainly from possible privacy violations.
To sum up, from a technological point of view this is very big (of course intelligence services have been using this thing for a decade now) but we should give it a good thought before launching it as it is. Besides, Google is already under suspicion because of its search engine (keeping user search entries) and its mailing service (filterning e-mail content to extract information). Finally, all this huge amount of data is becoming an invaluable source which is yet to be mined.