I've seen from the Windows API Code Pack that it is possible to enable custom glass in a winforms application, but I've been unable to ascertain how to get child windows to show as separte thumbnails for aero peek (in much the same manner that IE displays the contents of its tabs as separate windows)
Is it possible to do this from a Winforms application, or will it involve lots of P/Invoke voodoo?
The Windows API Code Pack contains what you need for this. Check out the Microsoft.WindowsAPICodePack.Taskbar.TabbedThumbnailManager class and related classes in the documentation.
These classes allow you to provide custom thumbnails and peek images to the taskbar, either from a Bitmap or created from a child control (presumably you can use an MDI child window for this as well, though I haven't tested it).