This is a post describing an issue a Swedish customer asked me about in the spring of 2008 that is described here. Since I still see questions on this I decided to post it here as well.
The problem is that when trying to access SharePoint from the link in the Group Membership dialog in Team Explorer they get the following error.
"The Team Foundation Server could not locate the online Site Administration application for this team project portal in Windows SharePoint Services. The most likely cause of this error is that the language settings on the team project portal do not match the current language of your Visual Studio client. The location of Site Administration is specific to the language of the project portal. Contact the Team Foundation Server administrator for availability information of Site Administration for this project portal. For more information, see the Windows SharePoint Services Administrator's Guide."
The reason for this is that Team Explorer picks up the locale of the operating system when constructing the link URL. In Swedish that would be /Sites/TeamProjectName/_layouts/1053 and since the 1053 folder doesn't exists IIS returns a HTTP 404 Error that causes the error message above to be displayed.
Because of how SharePoint works this can be fixed by adding an empty folder under C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\LAYOUTS on the server hosting SharePoint and name it the same as the locale you want to support. In my case 1053.
When the folder is found IIS is ok and since there are no files in the folder SharePoint will look in the default location for the files.
For a list of locales and their corresponding numbers I found this resource.
To make sure that you dont have any issues when servicing TFS I would recommend that you remove any folders added before trying any servicing