I was little frustrated with my WCF services not being hosted right on IIS. I kept getting the plain text .SVC file when requesting on IIS. I finally learnt that this is because of a nasty bug in the early WCF installation pieces. Looks like running the script given in the link fixes the problem
http://wcf.netfx3.com/files/folders/product_team/entry5648.aspx
Sigh....
Deepak.