You need to register in order to submit your results. Once a problem is resolved, you gain acces to a forum for that problem, where you can share your solution or read other solutions and, on some problems, a PDF with an explanation on the problem. As I have been developing Java for a couple of years I have found very interesting reading other solutions in other languages. In fact, I have started to learn functional programming because of it.
I resolved a bunch of them while studing for the Java 7 Programmer, using concurrency in almost all of them. A bit overkill, but very useful for learning.