Is that new or I missed it all the time?
I just installed .NET Framework 2.0 and some Express Tools and I noticed something (maybe) new.
When I open IIS Manager, right-click my website and click properties I have a new tab:

Then there I have a GUI tool for editing of my Machine.config and Web config - it looks interesting:

Or was it there all the time? Quick check... nope, on my .NET 1.1 machine there is no such tab.
So, I have something new&cool to play with :-)
UPDATE: So, this is definitely new :-) I'm used to manualy edyting web.config and machine.config, but it is anyway a great tool. Increases discoverability of .config features a lot. Best way to start playing with those files in .NET 2.0 and see what's new.