For all of the many directions Ubuntu One's cloud storage has gone, it hasn't headed the Mac's way. Official clients have been the province of Linux devotees (naturally, Ubuntu is recommended) and their Windows friends across the aisle. A newly available Mac beta puts all three major desktop platforms on an even keel, very literally -- the OS X port is almost identical to what you'd get in Linux or Windows, including a few rough points where other interface concepts clash. Still, the Ubuntu One test build has a handy Mac-specific menu bar item, and it's one of the few cloud options that will natively support both the Ubuntu box in your den and the MacBook Pro in your bag. Grab your copy at the source link if you can deal with a few unfinished elements.
Canonical Ubuntu 14.04