hmm, all I see at the online store is a 20 and a 60, leaving a huge gap in the middle, size and pricewise. Oh well, I'm not planning on purchasing for a few months yet, so who knows what will happen between now and then.
Apple introduced the iPod Photo at 40GB ($499) and 60GB ($599) on October 26, 2004. The line was then updated to 30GB ($349) and 60GB ($449) on February 23, 2005 (minus a number of previously included accessories). Then on June 28, they merged the iPod and iPod Photo lines to offer a 20GB ($299) and 60GB ($399). For more info, visit the Apple Press Release Library.
Apple seems to have settled on having only two models of iPod in each line: iPod shuffle (512MB and 1GB), iPod nano (2GB and 4GB), and regular iPod (20GB and 60GB) (with the iPod U2 being the current holdout).