The closed beta test began Monday for invited members of the Ubuntu user community, with further testers able to sign up by requesting an invitation, Canonical said.
Ubuntu One offers file synchronization for systems running Ubuntu 9.04, code-named Jaunty Jackalope, and is intended to be available to the general public in time for the launch of Ubuntu 9.10, code-named Karmic Koala, in October, Canonical said.
The system is integrated into Ubuntu's Gnome desktop software via a downloadable client, and once installed creates an Ubuntu One folder in the user's home directory, Canonical said.
When modifications are made to any of the files stored in this folder, the modifications are automatically uploaded to the Web service and propagated to the user's other computers, according to the company.
Users currently get 2GB of storage for free, or 10GB for US$10 per month, although Canonical said this pricing could change.
Individual folders can be shared with a third party via a right-click contextual menu. Once the folder is shared, it appears on the recipient's desktop in a "Shared With Me" folder.
Ubuntu One also provides a web interface that can be used to manage and access files without the need to use the client software.
Unlike competing services such as Dropbox, Ubuntu One supports only a single operating system, although Canonical said third-party developers could adapt the Ubuntu One client to other platforms such as Mac OS X or Windows. Dropbox supports Windows, Mac and Linux clients.
Canonical said it plans to add more features, such as synchronization of application data and preferences, as well as support for the KDE desktop software.