Then there is the fact that Google's fledgling music locker still requires users to upload songs to it manually.

ECONOMIST: The web giant launches a rival to Apple��s iTunes

Last week's Switched On discussed Lala.com's introduction of free music locker services that sync directly to the iPod (and only the iPod).

ENGADGET: Switched On: I'm in ur site, hearing ur t00nz

Google's music locker is currently free, but limited to 20, 000 songs.

WSJ: Apple's Music Service Stores All Your Songs Without Alot of Slow Uploads

The service is unlikely to be tied to an online music store like Amazon MP3, which gives users the option of adding new songs to their music locker at the time they buy them.

WSJ: Google to Unveil Online Music Service

With licenses from music companies, a locker-service operator could give users instant access to songs stored in central servers, rather than making those users upload every song in their music collections.

WSJ: Google to Unveil Online Music Service

The system Google is likely to unveil is known within the technology and music industries as a "passive" locker.

WSJ: Google to Unveil Online Music Service

Amazon.com (AMZN) late Monday announced the launch of Amazon Cloud Drive, a Web-based online locker service, with a particular focus on music storage.

FORBES: Amazon Launches "Cloud Drive" Digital Locker Service

Currently its locker accepts content only from the Web sites of customers that include Fox Music, Fox Sports Mobile, Sony BMG, TVT Records and Walt Disney .

FORBES: The Mobile Locker

Amazon's locker service has an impressive set of capabilities, which expand the value of owning music.

ENGADGET: Amazon updates Cloud Player with 256 Kbps matched files, faster import, direct delivery (update: Roku, Sonos coming soon)