I agree that PM should send the proper headers. That will fix the problem they have with PM. Now, what about the other >50% of the sites on the net that don't? Should their sysadmin (or the end user) be burdened with the task of contacting the admins of every site and asking them to fix/add the correct cache headers?

In a perfect world everyone's headers would be correct, then again in a perfect world nobody would use MS Word to generate HTML. :) Yes, the correct solution is that every site on the net should send the correct headers, HOWEVER the practical/realistic solution is to configure your cache. I would wager that it is possible to tell >90% of the time whether or not a URL is dynamic or not based upon it's construction and for that matter squid comes out of the box with a set of rules that have never needed to be tweaked.

/\/\averick
perl -l -e "eval pack('h*','072796e6470272f2c5f2c5166756279636b672');"