One thing I would like to see is a generalisation of the $ICONS/wbar stuff.
I am building/testing tablaunch, as it has auto-hide, something I sorely miss in wbar, and I'd like to be able to update it when a new extension is loaded. For my own setup, I can happily hack away at whatever part of TC to get it to do what I want, but that's not really practical for something I may submit for the repo later.
One solution could be a directory into which scripts of this nature could be dropped, and have /usr/bin/desktop.sh run the scripts in that dir, but I'm sure there are other ways to do so.