Geez ... sometimes the simplist things help so much :) Good catch, Dave. A good audit project for a bored hacker would be to go through PL/pgSQL functions making sure those that can be declared isstrict and iscacheable are so declared.
More granularity's been added, too, I think in PG 7.3. Another reason to revisit PL/pgSQL functions.
I did an audit of this sort on acs-kernel when isstrict and iscacheable were first implemented in PG, there were some noticable speed improvements as a result.
