In an effort to keep passengers from circumventing its $15 first-checked-bag fee, American has begun charging $15 to gate-check oversized carry-ons. No other carriers have matched this new fee (yet), but for the time being US Airways is saying passengers can continue to gate-check oversized carry-ons for free. United, the other airline with a first-checked-bag charge, is waiting to make a decision.
This new fee from American shouldn't surprise anyone, as one of the major criticisms of the first-checked-bag fee has been that passengers would abuse their carry-on privileges. This fee can even be seen as a good thing, because it will keep the overhead compartments free of full-size suitcases (OK, OK, new fees are never a "good" thing).
So the most inconvenient aspect of the oversized-carry-on fee may be that American takes your bag away from you. Not only will your wallet be 15 bucks lighter, but you and your bag will be separated. Anyone attempting to sneak an oversized carry-on aboard an American flight from here on out would be wise to put essential items for the flight (prescription medications, reading materials) in a purse or backpack that won't be taken at the gate.