TFS Workspaces across VS 2010 and 2012?

I am currently developing on Visual Studio 2012 RC using TFS Preview for source control. I would like to create an SSIS Integration project, which requires me to use Visual Studio 2010. However, when I connect to TFS from VS 2010, it automatically creates a new workspace and does not list the VS 2012 workspace.

If I issue the tf workspaces command from the VS 2010 command prompt, I see only the VS 2010 workspace, and if I issue the command from the VS 2012 command prompt, I see only the VS 2012 workspace (both indicate the same colleciton is being used).

Is there some way I can get VS 2010 to see the VS 2012 workspace? I would prefer not to have to have two copies of source code just to be able to use VS 2010 for the SSIS project.

TFS 2012 introduces a new concept called local workspaces, which differ subtly from the behavior of workspaces in previous versions of TFS (the old default behavior is now called a server workspace.) Local workspaces do not require read-only files and instead allow files to be edited without checking out from the server, and they are intended to be more suitable for small to medium sized workspaces. For this reason, local workspaces are the default in TFS 2012.

Local workspaces, however, are not compatible with TFS 2010 and TFS 2010 clients will not be able to use a new local workspace.

You can convert the workspace that you created with your VS 2012 client to a server workspace. In the Edit Workspace dialog, select Advanced, and you can change the type from a Local to a Server workspace.

At that point, you should be able to connect with VS 2010 and choose that TFS workspace.

(Note that it's not sufficient to use tf workspaces as that will return a cached copy of your workspace list - you will need to connect to the server either with Visual Studio 2010 or with a tf.exe command that talks to the server.)

In addition to the Location="Server" property mentioned in other answers/comments, the File Time property must be "Current", as shown below.

Workspaces created in Visual Studio 2012/2013 with either Location="Local" or File Time="Checkin" are not visible/usable in Visual Studio 2010.