Pensive and Media Kid are both Mike Church, a recent Carleton grad and current Wisconsin grad student who started posting on the law board after the college board got tired of him.
He recently had a huge-ass mental breakdown after an all-night posting spree making fun of Joe from Caltech, the preferred target for his jealousy. You may know pensive as the guy who views human relationships as equations, believes that if a girl doesn't like him she's "unprestigious" (the corollary to this, of course, is that "nearly all women are unprestigious"!) and apparently has something called Narcissistic Personality Disorder. He believes his invention of the game called "Ambition" to be a significant achievement--on par with founding a successful business--and expends a lot of energy trolling for it on the internet, trying to plant references to it in Wikipedia, etc., without too much luck. (Refusing to believe that the game is without merit, he attributes this to un-named forces out there in cyberspace conspiring against him, making repeated reference to a bunch of people he pissed off at Carleton whom he believes are behind this.)
He promised to leave and seek mental help after his all-night ragefest (which he professed not to remember at all the next day), and he actually did briefly stop posting--as pensive, at least. Remarkably, the posting rate for "Media Kid" skyrocketed right about this time, with MK's number one topic being, of course, how misunderstood and maligned "pensive" really is.
After a few days of being subjected to this, a fed-up Carleton alum on the board who knew Mike in person from school started posting excerpts from Mike's online "User File," a Carleton web board where he often argued with people at his school, the main topics being things like his card game, why he can't get a date, and how most women are stupid compared to him. Anyway, he did this in the form of a very funny Onion column by "taking questions" and then answering them with excerpts from Mike's writing.
A few days ago Mike abandoned all pretense and started making the occasional post as pensive again. That's more or less where we stand now.
I hope I've been able to bring you up to date!