Here's the fine print
EXPRESS LANE BONUS DETAILS (note: I omitted the original detail one, since it explains generically how you earn points on the HHonors Amex cards)
(1) This bonus offer is by invitation only to those who have been selected to receive this offer. To qualify, you must register for the Express Lane Bonus through the links on this page. If you are a new member or a member without a profile, you must also enroll and complete a dining profile during bonus registration. A dining profile includes creating a web login and opting in and remaining opted in to receive emails from Hilton HHonors Dining with a valid, deliverable email address. You must register by September 30, 2010 to qualify for this bonus. You must continue to satisfy Online or VIP Member level criteria to get this bonus.
(2) To get this bonus, you must dine within 30 days of your registration at any participating restaurants, bars or clubs. All dines within 30 days of your registration will count towards this bonus. For all qualified dines during the bonus period, members will get 15 points/dollar, and Elite members will get 24 points/dollar. Please note that activity that occurred prior to registration will not be eligible for this bonus. In addition, all dines must occur during a valid reward period and be paid for with a credit or debit card registered in Hilton HHonors Dining. There is no maximum number of HHonors Bonus Points that can be earned with this promotion. Offer is not combinable with other Hilton HHonors Dining bonuses. Please allow 4-6 weeks after you dine for HHonors Bonus Points to post to your HHonors account. All account inquiries related to this bonus must be received by December 30, 2010.