Fellow ASPInsider Phil Winstanley recently blogged about an issue he had been monitoring in an email thread. Specifically, the email thread was strongly leaning towards implying that the ASP.NET tab wasn't supported in R2 and x64 editions of Windows 2003 Server (which would have been a BIG deal).

Well, the email thread he was monitoring was one that I started. (And was on a private forum where Insiders can post feedback to Microsoft and get help/feedback from other Insiders and MS folks).

BackStory:
Normally when the ASP.NET tab isn't in place, that just means the Server hasn't been instructed to map any of its sites to ASP.NET 2.0 in IIS. Mapping is easy - just jump to C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727 (assuming that the 2.0 Framework is installed) in a command prompt, and run aspnet_regiis with the -i and -enable switches (or with the -sn <path> and -enable switches if you just want to upgrade a single site).

Only, I had done that, and a couple of other combinations - including uninstalling, re-installing, and even installing/mapping to lower versions (i.e. aspnet_regiis is installs whatever version of the framework the .exe is located in... so v1.1.4322 will do ASP.NET 1.1) and I still wasn't getting the ASP.NET tab to show up. (i.e. I had tried a number of 'vulcan death grip' switch options - but nothing).

Paranoia sets in:
I started to worry that maybe the ASP.NET tab wasn't supported in R2, and therefore launched an email thread - hoping that I had just missed something stupid. Another Insider with much better search skills than me (since I _did_ google first), pasted a link from the MS Office site  that surely seemed to indicate that there was a basis for my paranoia. Amazingly, it stated:

The ASP.NET tab does not appear on x64-based editions of Windows Server 2003 and Windows Server 2003 R2. This tab also does not appear if only one version of ASP.NET is allowed in the web service extensions.
[ exasperations added (original) ]

Worse, it repeated that notification over and over again throughout the page. Huh? What??!!

The Truth about the ASP.NET tab in R2 / x64 Installations:
Luckily Scott Guthrie noticed that my panties were starting to get in a wad (they do that some times), and put me in touch with some folks at MS to help look in to the situation. We weren't able to figure out what was up with my ASP.NET tab, but I did get some confirmation from MS:

The documentation on that Office page is false. In other words:

The ASP.NET tab is fully supported in all version of Windows Server 2003 R2, and is EVEN supported in x64/ia64 versions of Windows Server 2003 and Windows Server 2003 R2. The ONLY place that you won't see the ASP.NET tab is when you are running an x64/ia64 System and have IIS set to run in 32bit compatibility mode.

At this point I'm still NOT sure what caused my ASP.NET tab to disappear in my installation - likely just my incredibly good luck. That said, one of the caveats about getting the ASP.NET tab to show up is that IF you install IIS _AFTER_ you install the 2.0 framework, you have to run aspnet_regiis. (This wasn't my issue, I installed in the 'correct' order - and either way, running aspnet_regiis should make your ASP.NET tab display.)  So if anyone reading this is looking for their own ASP.NET tab - just run aspnet_regiis.

Conclusion:
Just for the heck of it though, I tried getting the ASP.NET tab in an R2 image, so I pulled up a Virtual Machine I was using for an upcoming demo and reverted it back to the 'base' image snapshot, then used the Add Remove Programs | Windows Components dialog to 1) add IIS, 2) Install the .NET Framework (it's an optional component on R2 versions of Windows Server 2003).

And, Wohoo! Everything worked -with the exact same IIS/ASP.NET options that I had chosen before. Still no idea what happened -  but some day I'll just repave (after I head to Costco and get a three-pack of chickens to sacrifice along the way, just to make sure).