It publicly releasing the IRL identity (name, address, etc) of the person behind an anonymous online identity. The term applies more to places like reddit/twitter/4chan than to someone's own blog, but it's generally considered a form of harassment because it's an invasion of privacy.
Ah! I didn't realize it was an English dictionary word. I really thought it was an "inner circle" term that needed defined for the layperson. My mistake.
