I've already enabled firewall rules for IIS Express (HTTP Traffic In) and IIS Express (HTTPS Traffic In) on ports 80 and 2012 (this one is used in WebMatrix), but I can't connect to the server from my LAN. WebMatrix is running on a virtual Windows 7 machine.
Is this a limit of IIS Express?> Yes - you can redistribute IIS Express with your applications. There are no connection limits. ScottGu's blog
Is it listening on local ports only, i.e. do you see 127.0.0.1:80 not 0.0.0.0:80 on netstat -an?
I haven't played with IIS Express yet so I don't know what the default is or how to configure this.
It is possible though it takes some effort, there's a great blog post on this here and Vaidy talks about IIS Developer Express on the CodeCast podcast here.
I was trying your same configuration and was unsuccessful in opening the Windows 7 firewall to just IIS Express. I was successful by opening the port I was using (80) to any application rather than restricting to just one application. My guess is that IIS Express goes through a service (HTTP.SYS?) and that needs to be allowed but I have not yet researched that.