Hehe.. that's actually kind of funny -- a cartel of sorts -- let's do like OPEC, and we'll all agree not to run more then 10 TH/s to make live easier for each other, and then we'll all cheat by selling our oil off-books .. er.., I mean running our extra hash through a separate pool from a different IP etc.. :-) -- I'm in!!
it only keeps going up as more mining power is added. if people stop adding rediculous amounts of power to the pool then the difficulty will drop. there were gentlemen's agreements proposed about things like this a while back. They go as far back as the transition from cpu to gpu.
https://bitcointalk.org/index.php?topic=12.msg54#msg54