Project / Properties / Startup Options
All of a sudden, I could no longer debug my project. After poking around for a while, I discovered that if I went to the webserver projects property tab, startup options I had to select "Silverlight Project". I don't remember unchecking this, but none the less, there you go.
I'm of course referring to my article of a couple days ago at:
https://peterkellner.net/2007/06/18/silverlightdebugwebservicedotnet/