I managed to get EntitySpaces running on Silverlight over WCF client proxies. I documented the steps as a tutorial and Mike Griffin at EntitySpaces posted it up on the EntitySpaces blog.

http://www.entityspaces.net/blog/2008/05/05/EntitySpacesAndSilverlightDemoPart1.aspx  

Demo here: http://developer.entityspaces.net/ES2008/Demos/Silverlight/PartOne/

I retained my Word doc so I can retain my personal preference of formatting, fix typos, and add a few annotations and disclaimers here and there like, "So far these steps don’t lend themselves very well to an offline development workflow. Finding a more appropriate workflow pattern, though, is beyond the scope of this initiative. (Good luck.)" We can thank Microsoft for making WCF on IIS 7 such a pain in the behind for binding service endpoints, without any code generation or GUIfication. But enough whining, client-side business objects in Silverlight is a hawt approach to LOB RIAs.

http://www.jondavis.net/misc/EntitySpaces and Silverlight Demo - Part 1.doc

Part two will be short 'n sweet but much more focused on actually working with EntitySpaces. This part didn't give ES justice...

EntitySpaces RIA running in Safari 3.1 (on Windows) with just about 20 lines of hand-written client-server code and XAML markup: