A stress test is performed on all MMO releases during their testing phase. What these guys are doing is basically performing a "paid" stress test. They make people buy the game in order to join the test until the servers can't handle any more people. When I buy an MMO I want to play with whomever I want, not a select few people who manage to buy the game while the store is still open. This whole phase is supposed to be performed in open beta, which never happened.
