Early days for Cider
If you have installed the December 2004 WinFx CTP most of you will know by now it has the VS2005 'Orcas' parts, and whats new is the visual designer for XAML (Cider).
Sam thinks it rocks, I would rate it as pretty cool, but also pretty useless. Its prone to crashing, the layouts don't work correctly and as a development tool it needs a lot of work. That said, its
early days so its to be expected and to see where they are heading is indeed very cool. However if you really want a visual layout tool for XAML, hang onto XAMLPad just a bit longer.