If Apple can't help you, depending on where the damage is it will be possible to remove the visible dent, but it will undoubtedly require disassembly. The only problem (apart from warranty and leftover screws syndrome) is that as a 'dead' metal, once the shell of the MBA is dented to a sufficient level undenting it still leaves a weak spot.
However, some people say that a dented aluminium something gives it character, that you actually use your gear instead of mollycoddling it - Just like some say for example that travel-worn Zero Halliburton cases for example look cooler.
I would say that it's a catch-22 situation in that generally speaking you have to mollycoddle an Apple otherwise it does suffer from damage in everyday handling unlike most other quality laptops. I also personally think travel-worn Halliburton cases look like crap and replace the ones I use often as soon as is practical to do so (thankfully less frequently than an Apple notebook), but YMMV.
