Apple Computer announced Monday that its new, fourth-generation iPod is available immediately through retailers and its online store.

As previewed in a front page feature of the July 26th issue of Newsweek magazine, the new iPod offers a thinner case, 50% better battery life and click-wheel navigation.

Key features of the new iPod are:

- 50% better battery life to 12 hours from eight through better power conservation.

- A click wheel identical in design and navigation to that of the iPod mini.

- A thinner iPod by one millimeter.

- More efficient menus, so there is less thumbing through to get to content.

- The ability to create multiple playlists and delete songs from them.

- Variable speed control to listen to content faster or slower.

The company reconfirmed that both the 20GB and 40GB models will cost US$100 less than previous models, making their MSRP $299 and $399, respectively. While not specifically mentioning the 15GB model in its press statement, the lower-capacity music player is no longer available as an option of the companyis online retail store site.