Apple today updated its iPod lineup with new 20GB and 40GB models. The two new models replace the 15GB and 30GB models previously available. The new 40GB iPod holds up to 10,000 CD-quality songs (playing each song back-to-back takes a month, notes Apple in the press release) in an enclosure that is lighter and thinner than two CDs. iPods are available in three models: a 10GB model for US$299, the new 20GB model for $399, and the new 40GB model for $499. All are available immediately.