In my experience, you can do anything you want, but as in with MP3 files, it's when it gets BIG and goes to people you do not know (which therefore implies you would be doing it for some FEE) that airlines or feds or music promoters,or any marketer, gets mad about it.

If you were to instead, "give" that award to some friend or family member, which is fine in the eyes of the airlines, then who's to say that person didnt give you a fine case of wine in return? Is there no value there? Is it illegal?

and if it were an airline flight award for your mom to fly to see her dying father or something, can airline X say there is some monetary value placed on love and family needs? They would probably not bust you there, so the line is certainly gray--in their favor.

Basically, it's like this:

They have discovered that people have found a way to trade off these unused, unwanted miles or awads thru the now widely used and trusted portal of EBAY. Sure, the rules of selling and fine print stated against it may have always existed, but the rate at which they were ever actually prosecuted were about as low as some cop busting someone who drives thru a stop sign in their own home town they know real well at 4am. You'd never really have to worry about being bsuted for that--unless the cop was a stickler and had it out for you, and had the NEED or perceived need to find and bust these peope (possibly for more internal perks at the job for himself) and also finally found an easy way to actually do it with little effort. (If the cop could use some computer terminal to see you--like with ebay transactions)

So yeah, Ebay, which is used by everybody, suddenly makes this little once-local act of trading or giving someone you know an award, become a huge money-making venture that the airlines know is getting you some coin, while they are still fussig about trying to figure out ways to bait and switch their customers. YOu found a way out and they want a piece of the action--or to prevent it. hey have, by bsuting people who they pick on the ebay highway, just like those other times when you get pulled over for doing 80, whilst the guy next to you gets away with it scott free.
(and who the heck IS scott anyway?)

that's my take on it.

Find someone at home or in the office who wants to fly. Make them give you lift tickets to your favorites ski area or great seat tickets to the next baseball game between the Red Sox and the Yanks instead! That's worth more anyhow.