CNN reports that Apple is in touch with record labels to try and improve the quality of the downloadable music it sells on iTunes and elsewhere. Currently, the MP3s sold on iTunes are formatted as 16-bit files, but under the new proposal, they'd be upgraded to 24-bit files, which means the files would have more audio data included, and thus be able to play out at a higher resolution.
As Chris Foresman at Ars argues, however, it may not matter. While higher quality is always nice to have (and there's no reason Apple shouldn't have it, unless the audio needs to be compressed further for streaming or other memory concerns), most people won't hear the full resolution anyway. You can have the highest quality audio files you want, but when you're playing them through a set of cheap speakers (or even the MacBook's default built-in speakers), you're not going to hear all of the highs and lows that you should.
Still, it will be nice to have the higher resolution, and it'll give Apple and iTunes yet another selling point if the agreement can be made (not to mention sell a lot of higher-quality audio speakers and other products as well). So, I expect we'll see it happen before long. Remember way back in 2007 when Apple raised the encoding rate to 256 Kb/s?