Jeff Davis figured this out (praise be his name!)
The problem was with the form type. In the adp file, I had style="plain" in the <formtemplate id="org"></formtemplate> section. This hasn't been updated to the 5.0 noquote stuff yet, so it was breaking.
I've posted a bug at:
http://openacs.org/bugtracker/openacs/bug?bug%5fnumber=1183
Thanks again, Jeff!