Well... I guess if you played 80 hours the past 2 weeks, i guess your a little addicted :b So i pretty much think that u can get addicted, but not the same way as with smokes, drugs or alcohol. Though there was some korean guy who played like 50 hours straight, ofc went to the toilet sometimes, and well... he died...
http://news.bbc.co.uk/2/hi/technology/4137782.stm