Powerball has not changed the Red Ballset since March 2006, or the White Ballset since August 2005, and as random as the numbers have been for the last six months, they don't need to.
FYI they have four different ballsets of each that they rotate every drawing, and four or six different machines they rotate between every drawing night as well.
They do not announce which ballset or machine they will use until the ticket machines are shut down prior to the drawing.
FWIW I have paid VERY CLOSE attention to the drawings per machine/ballset, and I just don't see ANY tendencies towards any particular numbers hitting (or not) based on ballset/machine. I wish I did, but I don't.
BobP - I kinda concur with you - the one thing I have noticed is if one number has hit 7 times with one ballset, it might drop to 2 times with the new ballset, and a number that has hit 2 times with one ballset might hit 7 times with the new one, BUT: for the most part, I see numbers that have hit 4 or 5 times with one ballset usually hitting 4-5 times with the new ballset as well. The latter is more accurate than the former in this paragraph. I don't see anything predictable. If anyone has, please share or PM me, and I will go look at my extensive charts.
Oh - and one last PS - if you DID find a number that is predictable, that is only ONE number, you still have to get all the others right.