Mac OS X 10.6 and higher
Users of the current beta version of the Mac client will need to install this new version manually, Canonical says, since the beta version didn't have automatic update functionality.
Designed for Mac OS X 10.6 and higher, the software is now available as a free download from the Ubuntu One site.
Users of Ubuntu Linux get 5GB of Ubuntu One storage for free; 20GB costs $30 per year. Through Ubuntu's referral program, you can also earn up to 20GB extra free cloud storage.
Do you use a cloud storage service? How important is cross-platform compatibility to you? Please sound off in the comments.