I’ve found that in Visual Studio 2008 Window.TileHorizontally and Window.TileVertically commands can be called to create a new horizontal or vertical tab group. I’ve tested it in SSMS 2005, SSMS 2008 R2 and VS 2005 – it works for them too. I’ve added these commands to the NewGroup add-in (that previously supported only VS 2010 with Window.NewHorizontalTabGroup and Window.NewVerticalTabGroup commands):
New tab group context menu commands in Visual Studio 2008
Download link: NewGroup v1.0.1.
Tabs Studio Blog (organizing Visual Studio document tabs) 