A new offer from United and Hilton The following from Bloomberg news:

BEVERLY HILLS, Calif.--(BUSINESS WIRE)--May 3, 1999--For the first time, Hilton HHonors(R) members and United Airlines' frequent flyers will be able to earn both HHonors points and Mileage Plus(R)
miles for all qualifying United flights. Called Mileage plus Nights, this industry milestone is being
offered by Hilton HHonors and United Airlines Mileage Plus from June 1, 1999 through May 31, 2000.
Hilton is already the only hotel company that allows travelers to earn both hotel points and airline miles for the same business-rate stay -- what Hilton calls Double Dipping(R). And now Hilton and United are taking the concept into the air, by offering one HHonors point for every Mileage Plus mile flown on qualifying flights.
"Mileage plus Nights is yet another exclusive HHonors promotion that we take pride in offering to our members," said Jeffrey Diskin, president and chief operating officer of Hilton HHonors Worldwide. "In recent months, we've broken new ground in terms of travel and merchandise reward options, and earning opportunities.