"Right up till the 1980s, SF envisioned giant mainframe computers that ran everything remotely, that ingested huge amounts of information and regurgitated it in startling ways, and that behaved (or were programmed to behave) very much like human beings... Now we have 14-year-olds with more computing power on their desktops than existed in the entire world in 1960. But computers in fiction are still behaving in much the same way as they did in the Sixties. That's because in fiction [artificial intelligence] has to follow the laws of dramatic logic, just like human characters." — Walter Jon Williams, interviewed by Bibliophile Stalker.
As Bruce Sterling pointed out, the problem is one of metaphors: Computers don't "think" so much as search and sort through information. A computer can no more become "self-aware" than a Rolodex can. Quoth the Bruce: "A tech world that chose to talk about ordinators instead of artificial intelligence probably would have produced Google in about 1980."