Edit: Also, I find it interesting that on a site so big (I mean MySpace, and thusly, on a site that should have a fair number of smart developers working on it), they have not changed the default IIS error message for something a little more site-specific and user friendly. To see what I mean, click the story's URL. :) Or is doing something like that deep voodoo on a robust web platform like .NET+IIS?
tagworld.com is really complex thing despite its simplicity from the outside. It has unique user base and handles around 1000 requests per minute. It uses around 20 web servers and 20 other servers for db, file storage, video/photo converting.
All code is written from scratch and .Net is great in maintaining the developement process. C# compiles and most errors get caught before deployment. In addition there is a buit in mechanism for validating dynamic pages, which also helps a lot. For some time we used to deploy the whole thing daily, with active users on the site.
.Net is more for the corporate world with lots of legacy code and outside apps. It just can't be done almost with any language except java.