I ran into a problem yesterday trying to create Avalon/Indigo projects in VS 2005 after installing the SDK (which has the templates).  After successful completion, the template types were not registered in the system.  Couple of hints to fix this:

1.  Make absolutely sure you install VS first.  Shut down all instances of VS and *then* install the SDK.

2.  The Avalon/Indigo templates are installed with a deferred registration. It can take up to 3 minutes after the SDK finishes to actually register everything.  So if you don't see the templates even after successful completion, wait a few minutes and restart VS.

3.  Worst case if you still don't see anything, you can fix this by doing:  "devenv /setup", for example:

   "C:\Program Files\Microsoft Visual Studio 8\Common7\IDE\devenv.exe" /setup

This is not yet in the readme but will be by the next CTP.  It is expected to get fixed for real before we ship the product.