Slush's pool is dropping off. Less than 16TH/s now and still dropping. Checked the global network hash rate and that has dropped from 155 to 152TH/s since last night.
BFL began shipping singles yesterday - I suspect the peaks and troughs are bfl testing the ready to release singles on slush's pool!
In a way its good if they are testing, it gives miners fore knowledge of the increases and wont go much above the previous numbers, should mean 1 big difficulty change and then a bit more calm.
from reading forums, the boost was because 50BTC was having connection issues so 4,000gh/s got shifted to slush around 9am est 6/12. it looks like 50% of that has shifted back...