PalmOS
Since the introduction of the first Palm Pilot in 1996, the Palm OS platform has defined the trends and expectations for mobile computing - from the way people use handhelds as personal organizers to the use of mobile information devices as essential business tools, and even the ability to access the Internet or a central corporate database via a wireless connection.

Palm OS 5, which has been available to customers for almost two years, supports ARM®-compliant processors. Palm OS Garnet is an enhanced version of Palm OS 5 and provides features such as support for a broad range of screen resolutions including QVGA, dynamic input area, improved network communication, and Bluetooth.

Palm OS Cobalt is the next generation of Palm OS. It will enable the creation of new categories of devices for the communications, enterprise, education and entertainment markets.

As with previous versions of Palm OS, Palm OS Garnet and Palm OS Cobalt retain application compatibility with existing 68K-based applications.

http://www.palmsource.com/palmos/