Jeremy. Just wondering about your thoughts on this usage scenario:
Part of a windowing application we have built (over several versions of silverlight - originally built in Flex 2!) has a simulated taskbar and start menu; well known ui patterns- MS and Apple have already spent lots on this type of user UX testing :)
Would you put these 'controls' in separate assemblies as well and use Jounce to re-assemble? [Moreover, the idea of creating a pluggable interface design via xap - WCF RIA pulls it together]
All UI resources are separate as well, I'm a big fan of as much abstraction as possible, particularly on look and supplemental function via MergedDictionaries.