According to CNN, Apple is working with record labels to offer high-fidelity, 24-bit music files on iTunes. Currently, Apple offers compressed 16-bit AAC files at a maximum of 256 kbps, but bumping to 24-bit could signal a change from lossy audio to a lossless format such as ALAC/FLAC.
Whether humans can even discern the difference between 16 and 24-bit audio is up for debate. Audiophiles can certainly distinguish between a low quality mp3 and FLAC, but once music gets up to the 256 kbps range, the difference is negligible. Apple could offer high-quality music at a premium for users with super-human hearing, but keep in mind that high bit-rate audio can quickly eat up storage space.