Interesting article on NewScientist.com:
Summary: Jonathan Huebner thinks that the rate of innovation has been slowing since the late 1800's, rather than accelerating.
Interesting stuff. The meta-takeaway is more visceral, though: it wouldn't just be unfortunate that technological advancements slow or halt, but the affect that would have on society - a new dark age.
I generally disagree with the interpretations of observations that Huebner makes, though. As Kurzweil and Drexler point out, if we hit key advancements (transhuman intelligence, nanotech) at any point, the ballgame changes substantially. It's a tipping point as big as the discovery of stone tools, fire, or agriculture. And those things don't follow simple trend lines.