A porn queen usually refers to a woman who has appeared in pornographic media, such as movies (porn flicks), magazines (porn mags), or online porn sites (webporn).
Many porn queens cross over between the different forms of media, first becoming a skin mag model, then later a porn actress; sometimes this process is reversed. Some porn queens even start their own websites. Porn queens also go on road tours, starring or headlining at strip clubs in major cities.
Being a porn queen usually implies the actress/model has made a "name" for herself. Often a porn actress will choose a fake name with a humorous and/or double entendre meaning so as to make it memorable (for example, Bunny Blue).
"...Jenna Jameson wants the world to officially remember her for her iconic porn princess name. Earlier this week the knocked-up starlet filed legal papers to become 'Jenna Jameson' and permanently move on from her birth name, Jenna Marie Massoli."
-- from Rumorficial Celebrity Gossip, Nov. 2008, on porn queen extraordinaire Jenna Jameson
(calling porn queen extraordinaire Jenna Jameson a 'princess' is like calling good Queen Liz a princess - a polite diminutive retrograde)