Anyone that hasn't already done so, contact your dealer and refer to Document ID# 1684809. They will order the replacement bushings that should eliminate wheel hop under "most circumstances" (from the TSB document) and install them under warrenty for you. The dealer might give you a little hassle about this proceedure as it is a TSB and not a recall but if you incist they must do the work. This is an excerpt from the TSB:
Important: Do NOT replace the rear sub-frame bushings unless the customer specifically has the concern of objectionable wheel hop.
EVERYONE should object to ANY wheel hop. The $160 bushings are a lot cheaper than replacing the rear differential... then again, the TSB refers to the action causing the wheel hop as being abusive and that's probably how GM would try to get out of fixing the rear differential under warrenty.
Give them a call and get your wheel hop issues fixed on GM!