The premise: According to Hotelicopter.com, a giant helicopter (a Soviet-made Mil V-12) has been transformed into a flying hotel:
The Hotelicopter features 18 luxuriously-appointed rooms for adrenaline junkies seeking a truly unique and memorable travel experience. Each soundproofed room is equipped with a queen-sized bed, fine linens, a mini-bar, coffee machine, wireless internet access, and all the luxurious appointments you’d expect from a flying five star hotel. Room service is available one hour after liftoff and prior to landing.
Reasons to think it's a hoax: a) it's a strange idea (how long it could fly before it would have to be refueled?); b) all the photographs of it are computer-rendered; c) the site is registered anonymously (what are they trying to hide?); d) no contact info; e) the site made its debut suspiciously close to April Fool's Day.
Probable perpetrator: It mentions Yotel, the mini-sized hotel rooms you can check into at Heathrow or Gatwick airports. So that would be my guess.