Check out, including full source in Nokia projects:
Great stuff! i also strongly encourage everyone to check the tutorials with create.msdn.com!
One thing I've noticed is that when people pick up a totally new platform they tend to take shortcuts in learning. That way they don't necessary realize all the possibilities that the new platform has to offer, and do things the hard way. Learn C#, learn SL/XNA from the ground up, it really pays in the long run.
I must say that when I have to train other devs on the subject, that time I learn the most, as I really need to brush up and learn deeply each subject. Sometimes I've stumbled on stuff that I didn't notice before even I've worked with the same stuff for years and I've learned to do things much more effeciently.