If you grill people hard on "why do you need all that complex, expensive crap anyway?" you can switch them over to Google Apps, or Zimbra, or LibreOffice + Evolution + SLES and have all the same functionality. Share point? What does share point do that WebDAV + Samba + Apache + some kind of CMS + MediaWiki can't, besides requiring an expensive share point admin and lots of licensing fees?
LDAP and kerberos have Linux implementations, but throwing the *nix way of doing this out the window in favor of the AD route is a really silly idea unless you need to integrate with existing windows crap. Basically, Windows perpetuates itself, and the solution is to drop it entirely and across the board.
>but throwing the nix way of doing this out the window in favor of the AD route is a really silly idea unless you need to integrate with existing windows crap.
This betrays a lack of experience with a large organization. The "nix way" is every program having their own configuration file with its own syntax and needing a signal (or restart the process) to change said configuration. Directories are far superior for this and it isn't a "windows" thing. It was Novell who first got serious with directory services.
LDAP and kerberos have Linux implementations, but throwing the *nix way of doing this out the window in favor of the AD route is a really silly idea unless you need to integrate with existing windows crap. Basically, Windows perpetuates itself, and the solution is to drop it entirely and across the board.