I've never worked with "Web Sites" and personally feel that a "Best Practice" is to not use them and Convert your site to a Web Application. Regardless - I would guess that Team Build treats them similarly.
For Web Applications (which it sounds like JackalDark is asking about) Team build should produce a "_PublishedWebsites" folder which should be the site you are producing.
There are a number of options - I have seen some posts about using the "Web Deployment Projects" on the MSDN Forums which should provide some guidance.
What I am doing at my current client is writing Powershell Scripts to copy the _PublishedWebsite folder to the appropriate production folder. What I do is have a "Config" folder tree for each Environment (my client has multiple QA environments and multiple Production Environments for their US, Canada, and UK businesses). Each environment will have the "web.config" and other config's used by Enterprise Library.
Under the "Deploy" Folder I have a "_deployApplication" Powershell script that calls accepts a parameter for things like the "EnvironmentName" (to select the appropriate Config directory" and the server name where the files will be copied.
I then have another Powershell script for each environment that calls the "_deployApplication.ps1" script with the appropriate parameter.
Since these scripts are powershell, there's hardly any automation task that can't be included, such as starting and stopping IIS if desired.
Other approaches for deployment I've heard other people using is to have the actual Deployment as MSBuild tasks and having seperate build types for each environment.
I personally prefer Powershell for my client as I hope to turn over the deployment functionality to a "Production Control" group that won't have knowledge of TFS and MSBuild. Another advantage of this approach - I just build off of "Tip" of version control and the builds site on the "File Drop" Location and the appropriate deploys to the various Environments can be run at any time in the future (as opposed to having to re-build - most likely from labels - which would be necessary if the deploy was MSBuild tasks as part of the build"