Recently, I had a little headache while deploying a WCF service to a win 2k8 machine running IIS 7.0.
The trick is WCF should get registered by the following command:
"%windir%\Microsoft.NET\Framework\v3.0\Windows Communication Foundation\ServiceModelReg.exe" -r -y
To read more about Service Model Registration Tool, visit the following MSDN page:
http://msdn.microsoft.com/en-us/library/ms732012.aspx
Enjoy!