vsdbcmd 'built by a runtime newer than the currently loaded runtime and cannot be loaded'

When deploying the latest version of our application to the Production server we got this error:

Unhandled Exception: System.BadImageFormatException: Could not load file or assembly 'vsdbcmd.exe' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded. File name: 'vsdbcmd.exe'

Oh god, I thought. Yet more VSDBCMD wierdness. But this box had SQL Server installed, so the normal 'needs SMO / Batch Parser' caveats didn't apply. Eventually I ILSpy'd the assemblies to check the bittyness, and guess what! The error message was completely accurate. I'd accidentally picked up the VSDBCMD not from the VS 2008 folder (9.0) but instead from the VS 2010 folder (10.0). Which is .Net 4. Which really is a more recent version of the runtime than was installed on the Windows 2008 R2 server. Embarrasing to be caught out by a completely accurate error message (though if it listed the versions involved I might have paid attention)