While all the details aren’t out yet, it appears that Priority Club is matching Starwood’s free weekend nights promotion between May 4 through July 3. Check out this FlyerTalk thread for all the analysis you could possibly want.
There are two major things that appear to be different about this promotion. On one hand you can either earn points OR credit towards a free night, and whichever option you go with is the case for the whole promotion period. Given how many points can be earned with Priority Club through the various promotions, it might not be worth participating in this promotion depending on your travel patterns. On the other hand Priority Club’s free nights can be redeemed on any nights of the week, and not just weekend nights (like Starwood).
It will also be interesting to see whether other hotel chains match. If anyone matches, I’m putting my money on Hyatt.