Microsoft released LightSwitch Beta1 yesterday. If you already have Visual Studio 2010 installed, then LightSwitch package is added to the main IDE. If you install LightSwitch on a clean machine, customized VS IDE is created for development:
Visual Studio LightSwitch Beta
To run Tabs Studio in a standalone LightSwitch IDE, first install stdole.dll in the GAC. Other than that, Tabs Studio works in LightSwitch IDE as usual:
Tabs Studio in Visual Studio LightSwitch Beta 1
Tabs Studio Blog (organizing Visual Studio document tabs) 