Thanks anon...Limit Logon testers have just been notified that the beta test period is nearly over. A public release will be avaliable soon.
"Thank you for participating in the Beta Test program for LimitLogin. We are pleased to announce LimitLogin will be available for download on Microsoft web site soon. Your bug reports and suggestions for improving LimitLogin have helped us to build a great product."
LimitLogin adds the ability to limit concurrent user logins in an Active Directory domain. This tool will be released as a resourcekit tool for Windows 2003, it requires IIS 6 and is not supported (as all resource kit tools). The tool is 3.55 MB. Read more for further information.