ComponentOne "Sapphire" is a set of UI controls for Silverlight 1.1. The animations on some (especially the hyperpanel) still need work, but overall, this is a really nice and complete set of controls. They even include a number of the missing panel controls. I would expect a number of these controls will be redundent when the final SL 1.1 release comes out, but choice is usually a good thing.

I wish I had it when we built the Carbon Calculator back in May [:)]. One of the more time-consuming tasks on that project was creating the drop-down listbox from scratch

I haven't yet looked at the implementation, but I'll be curious to see how they did styling. That is one area of Silverlight that is likely to change quite a bit between now and release, and I'd hate to lock in to a proprietary styling mechanism if templates and styles will be coming (and no one has agreed that they definitely are) in the final 1.1 release.