Hi I have extensively tested your plugin that is very usefull in our company (Smile 1000+ users)

I have developped a few enhancements :
set_traces_in_console(p_enable) to disable traces in the console (polluting mongrel log files)
manage groups members in a singleton hash (to keep them in cache for 120 seconds for example)
fix groups addings and deletion
manage single ldap connection
nice traces in logs
etc...

Feel free to integrate to your code