Has North Korea gone mad?

This is what all people is buzzing about. Has North Korea gone mad? do I sense jealousy to South Korea? Are they just getting attention so as to boost their economy? no matter what the reason(s) is better prepare for the worst. Here's a link from the yahoo news of their analysis on the incident. 


http://news.yahoo.com/s/ap/20101123/ap_on_an/as_koreas_clash_analysis