According to Wikipedia Pollard’s rho algorithm was invented in 1975 and Quadratic sieve in 1981, so all of the ~10 quadillion fold improvement occurred over six years. The 1977 vs 2007 hardware makes appreciating just how big that improvement was a bit more intuitive, but doesn’t tell much of anything else. More data points are needed.

Speaking of which my statement “but still exponential” above is stupid. Again, more data points needed to say anything.

http://lists.extropy.org/pipermail/extropy-chat/2007-August/037450.html

which points to this:
http://dwave.wordpress.com/2007/08/27/algorithms-vs-hardware-the-throwdown/