Server Side PL support

I have been taking a brief look at pltcl, and particularly its ability
to preload modules. By comparison with most of the core product this
seems to be somewhat out of date and unpolished (e.g. hardcoded path to
libpgtcl.so, no use of schemas for the supporting tables, lack of
comments). Since my understanding of tcl is extremely rusty, I didn't
dig further than that. However, I am interested in getting a similar
facility working for plperl, and thus wanted to start a discussion on
what general facilities could/should be made available to server side
PLs. Or should we just assume that each PL will create it's own support
tables?

cheers

andrew