There is an acs-ldap-authentication package in the OpenACS4 CVS.
But, I don't think it has been ported, the status page shows it lacks a person to do the porting work. Also, it seems to use some Java functions...
Overall, it looks like something Matt could use, if it was ported and working for OpenACS. Matt... did you just volunteer to port that package for us? 😊
Worst case, at least reading its documentation looks like it would be worth your while.
