This will be yet again an all time high difficulty increase. We are experiencing quite interesting times I believe.
I guess the next all time high change will be when Cointerra gear (hopefully) hits the market...It takes approximately 1227pcs 2TH units to provide the current network hasrate. I think they have a lot more preorders than that.
There had been a 300 % increase on 16th July 2010.
The difficulty had changed from 45 to 180. (Yes, 45, no millions, no thousands.) :-)
[edit] I haven't been mining at that time, just have found the data in the blockchain now.
