Though Utah only recently started their rebuild, they already have a bunch of young, talented players. They lack a dynamic point guard. How about this:
With Big Al on board, the Celts not only have more depth where they need it most - up front - but a player they can move forward with once the Big Three retire or assume supporting roles. Furthermore, he would probably actually want to be here unlike DH12 and the rest. Meanwhile, the Celts would still be under the cap in 2012 so they could use the full MLE on someone - Nick Young maybe... the full MLE would double his '11-'12 salary.
Harris is a downgrade from Rondo - goes without saying - but he's a decent defender and he can score. If I remember correctly, he's had some health problems but who hasn't?
I'd call that an upgrade - overall - and with Jeff Green coming back next year, the Celts will have a playoff-caliber core of young guys. Not in-their-prime Big Three caliber, but definitely competitive, especially if they can sign a youngish veteran with the MLE and draft well with at least one of their two 2012 picks.
P.S. I know Al Jefferson is not a real center, but neither is Jermaine O'Neal. He and KG will match up with opposing teams as best they can.