Currently were looking at 450 Th/sec that we expect to enter the network between September and the end of October, Cole predicts. That will mean substantially increased difficulty as more miners come onstream.
Sam Cole KnC
http://www.coindesk.com/a-look-inside-kncminer/That was back when they thought their products were 400GH. So now that they might be 500GH? Make it closer to 600TH I think?