Time Machine when logged out on LION

Hi.

Does time machine backup the local system disk when no one is logged in (not the one set up in server.app)? We only use AD users and the only one logging in is the admin, and we backup to an external ethernet disk.

In the old days you could make a automount.plist that keept the mounted disks when logged in.

http://hints.macworld.com/article.php?story=20031103155828117

but ive seen reports that it dosent work on lion and is causing some major booting problems.

So is there any solutions around for making it backup?