David Wang's already blogged the issues the IIS team has run into getting Debug Diagnostics onto the main download site.
Until we get Debug Diagnostics up on the Microsoft Download site, you can obtain the RTM Debug Diagnostics pieces from the Microsoft Beta site. Go to http://beta.microsoft.com and use the GuestID DebugDiag. You can obtain DebugDiag and a useful slide deck explaining some of the main functions.
If you attended Microsoft Tech.Ed 2005 there was a session on DebugDiag. I was lucky enough to present the session in Australia, and I'll see if I can get permission to post the slide deck up here. If you were attendee, you can get the deck from Commnet.