One bugbear that always annoyed me in v1.x of .NET was that the only way to specify that you wanted the server GC to run for a service was to write a stub host in C++. Today I had cause to look to see if this was still the same under Whidbey and I'm happy to say it isn't. I can across this post by Chris Lyon.
The crucial bit for me is this:
<configuration>
<runtime>
<gcserver enabled="true" />
</runtime>
</configuration>