One lady told me there are not gonna any improvement for cut off date for all categories in 2006, they already used up visa number. So she suggested me to check cut off date in September, i.e. for 2007 quotes. She even told me there is no need to check August VB, it should be the same with July.
Not sure if she's serious, I urge other people to call 202-663-1541 and press "0" to get more feedback from visa specialists. I guess some of them may really know the answers.
Be prepared for bad result :-(