A Billboardstory this weekend discussed the rise of flash memory drives and bracelets as a medium for album releases. I knew that had experimented with selling USB bracelets of live recordings, but artists like the Mars Volta and Ringo Starr are also offering new albums on USB. So far, because they're more expensive to produce than a CD, most artists are selling them as niche products for the biggest fans--for example, the Mars Volta is offering a monthly download to fans who pay $30 for the USB version of their last album, The Bedlam in Goliath, and Radiohead's former record label, EMI, is offering a live show download to fans who bought the USB drive containing all seven of the band's EMI albums. Eventually, though, as memory prices continue to drop--as they inevitably will--USB drives could become a mainstream product.
Companies like All Access Today and Aderra are already promoting services where they'll record you live and immediately press the recording on to a USB drive for sale at the show, so I'm sure independent artists could strike a deal with them to press a limited number of new albums on USB as well.
So while the CD's certainly not dead yet, its physical replacement is in the market today.