Over on the Nerfbat blog, Ryan Shwader is attempting to break down the concept of being a hardcore gamer starting with this post. He's started by looking at time spent in teh game and he promises to look at other concepts such as skill. I've had this on my list of things to study for awhile - ok for like the last 4 years. I'm glad to see someone tackle it and I"m going to be reading.
Check out the comments - why do people seem to react so violently when folks try to define things like hardcore. Why do they feel threatened or feel the need to ridicule? Very strange.