A common security/performance setting is to disable short file names (aka 8.3 file names), and is recommended as part of the Microsoft Solutions for Security (MSS) (Disable Auto Generation of 8.3 File Names [NtfsDisable8dot3NameCreation]). However, as one of my customer's recently discovered, this is an as-of-yet-undocumented prerequisite for System Center Configuration Manager (SCCM) 2007. The SCCM prerequisite checker will throw several errors: "Short File Name (8.3) Support (Site system)." This is not currently listed in the list of prerequisite checks or the release notes.
The inside scoop is that there's an issue with Windows Installer and the SCCM Administrator Console that necessitated this check. It came up last minute before RTM when the documentation was already locked. It should appear in the updated documentation when SCCM becomes generally available in November.
See How to Disable the 8.3 Name Creation on NTFS Partitions for how to enable/disable this setting.
Thanks to Wally Mead and Jeff Gilbert for the info.