Actually, the iPod never had it as a supported feature (thanks to the RIAA). You can still do it, all the music is in a hidden folder on the iPod, which has never changed. It’s a little harder to find now, though - they just changed the name to something less obvious than “Music”.
The cheapie MP3 players allow you to do that because they’re not paired with a store. None of the store-linked players allow you to copy back files from the player to another computer in the same form. The store linked ones have to abide by agreements with the major labels, so no “official” copyback.
Oh, okay. Thanks for the information!
But iTunes did have a feature to do the same, which they disabled subsequently. Here is a link I just found:
http://www.engadget.com/2004/10/30/itunes-4-7-disables-ipod-download-application/