I've been experimenting with particle generation a little bit over the weekend. The basics seem to be there, it does emit particles after all. Most of the issues that I've been running into are related to performance. There really isn't a "lightweight" way to generate all those particles, so I end up just creating hundreds of ellipses and moving them around the screen. Given what I'm doing, I think that Silverlight's doing a pretty outstanding job keeping up...but I wish there were a lighter-weight way to handle these kinds of drawing operations. In WPF, I would override OnRender for the control and then just issue drawing commands.
Finally, as always, if you do end up doing something with this I would really love to know about it. Please send email to email@example.com. Knowing that people use it is the fun part of putting stuff out there.