We are using TFS 2010 with visual studio 2008 so config transformations are not an option.
Our solution builds four sites. In each Web site project there is a web.config we use locally and a config/devel.config and a config/live.config. Our current TFS 2008 build development build copies devel.config over top of web.config while it is copying the site to the server.
We are trying to use the new 2010 build types to solve some issue we had with the old builds. For reference this is the lines old msbuild
<!-- Copy the Files to the devel Directory -->
<Copy SourceFiles="@(DeploymentTarget)" DestinationFiles="@(DeploymentTarget->'\\server\site-Trunk\%(RecursiveDir)%(Filename)%(Extension)')" ContinueOnError="true" SkipUnchangedFiles="false"/>
<!-- Copy the Web.Config File to the develtest.nanaimo.ca Directory -->
<Copy SourceFiles="c:\tfsdump\Binaries\Release\_PublishedWebsites\Deployment_site\config\devel.config" DestinationFiles="\\server\site-Trunk\Web.config" ContinueOnError="true"/>