Having problems getting the Access Control Service UserNamePasswordCalculatorService sample to work due to certificate problems? The issue may be that InstallCerts.bat may not be installing the certificates correctly. See the following thread for how to fix it:

http://social.msdn.microsoft.com/Forums/en-US/netservices/thread/1d09fc5e-fbbc-4e98-b14b-ab69c0d9e1c4/

Also, if you're using a beta version of IE8 with Vista and get a blank screen when associating a CardSpace card with your account, see this thread on showing the site in compatibility mode:

http://social.msdn.microsoft.com/Forums/en-US/netservices/thread/30ba7abe-5808-4acc-9d10-20c585b8f3e2/