In her latest post over at her DevLife Developer's Blog, Julia Lerman discusses her first experience using a Microsoft Support Incident call:
Even though I have access to search engines, newsgroups and some very smart developers, talking to someone who's focus is ASP.NET support is a huge advantage.
I've never had to use one of those calls myself, but I'm sure the day is coming. From reading Julia's post, it does sound like it might be worth the money if you have to pay for the call, depending on how critical your problem is.