Looks like it's valid for new card members in August and September according to their website.
http://riverscasino.com/desplaines/promotions/new-member-500-payback//
And yes, looks like you get a "rebate" in the form of free play for next visit on your one-time/first-time visit when you sign up for a card up to $500.
I've never been there but will probably go in the next couple weeks to sign up and take advantage of the offer.
Scott
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________________________________
From: Chandler <chandler_re@comcast.net>
To: vpFREE_Chicago@yahoogroups.com
Sent: Friday, August 17, 2012 8:49 AM
Subject: [vpFREE_Chicago] Rivers "$500 New Member Payback"
Anyone have any information on this promotion? I noticed it advertised on a billboard on the way back into town last weekend. Stopped by the rewards desk while there last night and boothling was completely useless. There were hundreds of printed cards advertising the promotion on the counter right in front of him and thousands more stacked up behind him, but he couldn't tell me if the promotion was currently running and said it might not be. The advertising said see rewards desk for rules. No printed literature on rules. Don't know if I want to depend on this guy for explaining the rules, but it sounded like a loss rebate promotion. Didn't bother signing up for a card.
Chandler
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