I've been recently reading 'Halting state' which is an amazing book by Charles Stross on the what will happen as the Internet becomes more and more ubiquitous. Among the technologies he uses in the plot is continuous Internet as a HUD (heads up display) this sort of HUD would be projected onto what you see from a pair of glasses giving you anything from the best route to your destination (think an iPhone whose screen you see all the time).
Most of this technology already exists (see the sixth sense prototype), iPhones supply constant GPS capabilities, 3G phone systems allow for some degree of Internet access almost anywhere (the newer 4G will improve this massively). Things like the cloud and the grid give constant wifi connections. MMORPGs (Massively-Multiplayer-Online-RolePlaying-Games like World of Warcraft) are becoming mainstream and as they become less esoteric and video games become a common media more MMORPGs will crop up. Urban gaming is already appearing with examples such as geocaching or the more paranoia inducing StreetWars.
In terms of non-existent technology only the ability to create overlays onto the real world are missing and this has moved a lot closer to reality with the creation of a .97" screen by the American company Kopin the big thing about this is that at less than an inch they have created a fully functioning 1280x1024 screen (that's the same resolution as a standard 19" monitor). While an inch screen sounds like the ultimate in eye-strain-o-vision at the distance of a glasses lens it is reasonable to view.
At most much of this technology will happen within the next 10 years or so, the full overlay technology may take a little longer but if nothing else we are now (pretty much) fully capable of hooking a good webcam to a pair of glasses and running the lens as screens. Of course what happens if someone hacks this would be pretty horrible.
UPDATE 1340 03/07/09: this news just broke. The theft was via standard abuse of privileges (something that is not punishable in eve although the subsequent sale of the kredits is) while the value of the theft was ~£3,000 and technically hard to punish legally it will be more and more common and is only a matter of time before someone starts testing this legally.