A great blog posting at the Official Google Webmaster Central site dispells some of the confusion over dynamic sites that pass parameters in the urls.
They go on to warn that bad url rewritting may in fact do more harm than good.
The comments are filled with lots of opinions and some anger, but overall I think it was a great post from Google. There has been a lot of folks who have long said dynamic urls are penalized – and apparently that’s not the case.
With that said, I am more likely to click through on a link like http://www.online-store.com/men/shirts/ than I am http://www.online-store.com/cjb.asp?fx=sshyw12j&loc=1191881881&dz=ahj
The other thing to keep in mind is that this is “only Google”.