So Google recently announced its Project Glass, augmented reality glasses to put information not just at your finger tips, but in front of your eyes all day, every day (check out the snazzy video). What it showed isn't available yet, but anyone who thinks this is science fiction that won't become fact is deluded. This is just the next iteration of our desire to have access to information as quickly as possible wherever we are. Smartphones are the current pinnacle of this need, but it was always bound to move forward and projected screens are the next step.
There's already been talk about contact lenses that can project images in front of your eyes, which are already showing promise and are probably the next step after the glasses/goggles that Google is suggestion. After that you're probably looking at something to influence the optic nerve (they're basically electrical impulses after all), initially outside the skull, but eventually buried in your skull. To support this we're going to need new ways to interact, speech isn't going to cut it in all instances, so some sort of pupil or thought navigation would be my guess.
Mind you, if you think the technology in Google's demo video is unlikely to see the light of day for a long time, that it's just a video filled with CGI, you'll be surprised to know someone has already knocked up a prototype using available technology. That's not to say there aren't problems to overcome yet. There's no suggestion what provides the processing power, or what the the battery life's like, or what it weighs or how it connects on the go.
One problem with constant access though, will it just mean we end up being pestered by adverts everywhere we go?