While browsing around my newly installed MMC 2.1 Beta 2, adding the various snap-ins that you tend to use while working with BizTalk 2006 I stumbled across an Enterprise Single-Sign On Snap In. I don't recall this being part of BizTalk 2004 and although there doesn't tend to be much to it, I can see some of the information that it presents being useful. I have included some screenshots below.
The new snap in as presented in the left hand navigation pane of your MMC.
The information shown if you click on the Affiliate Applications node in the left hand navigation pane.
The information shown if you click on the System node in the left hand navigation pane.