One thing's for sure, Petty will release two or three albums before we see a new Fleetwood Mac album!
At least, with playing with "Mr. Canplayeverysongintheworld" Benmont Tench, Lindsey'll pick up a few things from working with them...as much as they'll learn a few things about record production from Lindsey.
If "Walls (Circus)" from the "She's The One" soundtrack is any indication of how this collaboration will work out, I'm almost looking forward with more anticipation to Petty's new album than I am for Fleetwood Mac's.