If you've used this hint to enable Time Machine backups to non-supported network drives, this hint is for you. In particular, your backups are in danger. I have received a few hint submissions warning about problems with these disks, where everything seems to work fine at first, but when the SMB drive fills up, Time Machine will quickly destroy all of your backups! This seems to happen because Time Machine can't free the space inside the networked sparse image bundles (or the reported space is incorrect). Whatever the cause, Console will show all of your backups being removed once the networked drive fills up.
I have placed a strong warning on the original hint (as this issue is noted in the comments there, too). However, I felt it worth running on its own for anyone who may be using an unsupported network drive and isn't yet aware of the impending troubles they will have when it fills up. You have been warned; for now, this is not a usable backup solution, it seems. (I don't know if limiting the size of the backup, as per this hint, would solve the problem or not.)
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007121706402296