After the Debian Potato to Woody upgrade, all but one of my Python cgi scripts stopped working. The only one that still worked was a trivial test script to print out the OS environment parameters.
Tonight I lucked onto the solution. I have been using my own Python install of release 2.2, because DreamHost used to just have 1.5 installed. Now, Python 2.1.3 is installed, which at least is a lot better than 1.5. On a whim, I changed the #! line at the beginning of one of my failing scripts to point to /usr/bin/python rather than my local install. That fixed the problem. I updated all my Python cgi scripts to point to /usr/bin/python and now they all work.
I have no idea if Perl CGI scripts might have the same problem. However, if you created a local install of Perl just because you couldn’t wait for DreamHost to install 5.6 and you are getting CGI Internal Server errors every time you call your CGI scripts from a browser, I recommend trying to use /usr/bin/perl.