The Jasper's only just starting to turn up in stores; if you're buying a 360 over Xmas you'll probably end up with a (crappy old generic) Falcon, as the boxes aren't differentiated in any particularly obvious way and I'd bet money on salespeople not knowing what you're talking about. The only way to beat the system and take home a Jasper is to be Clued In (TM). Clued In people are the best kind of people.
Bill at Dubious Quality offers the following advice on snagging a Jasper:
Can you tell from looking at the box? Possibly, and here's all the information I can give you.You can read Bill's full post over at Dubious Quality. (link)
1. On the outside of the box, the bar code sticker will include a "team" and a "lot number." The team must be "FDOU," and the lot number must be "843x" or higher. Please note that finding an 843x unit doesn't guarantee it's a Jasper, but any lot numbers below almost guarantee that it isn't.
2. The power supply is 150W, with an output of 12.1A. By comparison, my repaired launch unit has a 203W power supply that outputs 16.1A. Falcons have a 175W power supply and output 14.2A. The problem, of course, is that you won't know what the power supply is until you open the box.
3. If it's an Arcade unit, the features comparison on the side of the box must list "256MB" as the memory. The new Arcades come with 256MB built-in flash memory instead of the 512MB flash memory. All I've seen reported so far as Jasper units are the Arcade models, so it might be another few days (or weeks) until they start showing up in Premiums and Elites.