This was yesterday in the MtGox IRC channel:
17:31 < kinlo> there is something wrong, how can it have gone above 10 when my sell order at 8 didn't occur?
17:31 < molecular> it didnt reall go above 10, I assume
17:31 < Ymgve> kinlo: bugs, the orders didn't happen or there was something wrong in the matching algorithm
17:32 < kinlo> MagicalTux: ?
17:32 < molecular> likely has to do with the "new currency markets"
17:32 <@MagicalTux> no
17:32 <@MagicalTux> has to do with hackers trying their best to do stuff normal people wouldn't by dropping large amounts of stolen funds/coins
...
17:35 < molecular> flushing bad orders? How do I make a "bad sell order" at 30 USD? ^^
17:35 < xelister> molecular: =)
17:35 <@MagicalTux> molecular, I blocked ~2000 accounts created most likely for the purpose of killing bitcoin on 9/11
17:35 <@MagicalTux> their trades do remain however
17:35 < molecular> MagicalTux, holy moly!
17:35 <@MagicalTux> but they cannot execute, causing weird results
I must say, it would take balls of steel to fuck with people who have stolen a large amount of money and wish to capitalize. If one does not have a pretty good sense of their dispositions and means at least. That would be a much bigger commitment to Bitcoin than I could ever muster.