In earlier post I provided one way to enable automatic token replace when building a WCF service for SharePoint 2010 (but this tip applies for any project really), here is what I said
Setup token replacement, see http://msdn.microsoft.com/en-us/library/ee231545.aspx
Essentially, this minimizes the need to manually add things like a 4-part assembly name. After all, the solution already has that information so why not have VS2010 do the work for you.
Navigate to Program files (x86)\MSBuild\Microsoft\VisualStudio\v10.0\SharePointTools
Open up the Microsoft.VisualStudio.SharePoint.targets file and locate the TokenReplacementFileExtensions node.
Add svc to the list of replacement extensions
The above is ok and works for all your projects except that the file will/could be overwritten by service pack updates. Another way to handle this is to open your *.csproj file and locate the <TokenReplacementFileExtensions> element and add the svc extension directly into the project. Again, see the specifics in http://msdn.microsoft.com/en-us/library/ee231545.aspx