"We are offering a 50% Rebate on all purchase made via Paypal or Credit Card between 12:01 am on 5/28/11 and 11:59 pm on 5/30/11 (US/Central) ... The Retail Price of all of the works on the site remain the same as previously set by the publisher. Customers will be paying full price and your commissions will be paid off of that full price as usual. The cost of the promotion is being carried by all romance."
Edited to add, apparently the rebate is in store credit only. This could be clearer in the announcement IMHO.