I recently saw this TED presentation on Sixth Sense, which is pretty cool. It ties in nicely with the research I've been doing as part of my Rememex project. It seems, for all intents and purposes, to be a fairly full-featured digital recall system. It's just a shame that it looks like you're wearing one of those pneumatic bank drive-through canisters around your neck. The video does a better job of explaining the technology than I can:
My interview with Gordon Bell discovered that, in function, his apparati were capturing all manner of interesting data, but it was still a battery of devices necessary to perform that capture. The idea will never become mainstream if we're required to put on a sweet of sensors as complicated as a hockey goalie's uniform. The more quickly we can get to a point where the sensors converge on a single device (Star Trek tricorder, anyone), the sooner we'll be able to reap the benefits of comprehensive data capture.