Truemors reports that IBM has build a computer that can do 1 petaflop, which is 1e15 (1 with 15 zeros after it) calculations per second. According to the commenter on the same article, the human brain is estimated to have a capacity of about 2e16 calculations per second, or 20 petaflops. So this machine has a theoretical capacity of about 1/20th of a human brain. Big deal.
On the other hand, Moore's law tells us that processing power doubles about every 18 months. About four-and-a-half doublings gets you to 20x, which works out to just under seven years.
In my last post, I talked about John Gruber's calculations that we moved computing technology from desktop to smart phone in about 7 years. For rough numbers, lets call that $2100 down to $700. And the size went down much more than that.
Ray Kurzweil has done the complete math on this, but basically we can count the days until you can have a computer in your pocket that is as smart as you, for a few hundred dollars.