What are some good resources for learning threaded programming?

With the rise of multicore CPUs on the desktop, multithreading skills will become a valuable asset for programmers. Can you recommend some good resources (books, tutorials, websites, etc.) for a programmer who is looking to learn about threaded programming?

I've honestly never read it myself, but Concurrent Programming in Java is a book I've heard recommended by several people.

http://www.cilk.com/multicore-e-book/

That's a nice general overview of the sitution, if you're looking for tuorials and books it might be best to specify a language as a starting point so you can mess around with some code.

Take a look at Herb Sutter's "The Free Lunch Is Over" and then his series of articles on Effective Concurrency.