Just like Josh Smith I was looking around for some pre-rolled themes for WPF, and wondered why there was so little activity in this area. I would have thought the ability to take a professional looking UI (adjusted to match an organization's in-house style) would be a popular approach for building new business applications.

Although there's quite a bit of work involved in creating a complete set of control templates (for all the required controls; textboxes, dropdowns, checkboxes, tab controls, lists, splitters, scrollers etc.) it can  be done (and it's a great way to learn WPF - even if you only override a few). Included here is a screen shot from my 'learning' WPF application in which I created a nearly complete control template set from scratch - including a custom toolbar strip, and dropdown/context menu system. What's more I give the user some options on basic color themes and backgrounds - just like Windows Live Writer does.

Commercially available themes must surely be on the way. Maybe they're just waiting for WPF adoption to reach higher levels, or perhaps visual designer support to improve. I'd estimate that it would take about 20 person days to complete a full theme set - and that's with a good graphic designer working with a good WPF developer together to assemble the theme.