BitTorrent labs has released an alpha of it’s new BitTorrent Sync, which uses 256 Bit encryption to securely sync data between multiple computers using it’s Bittorrent Network. Not truly a cloud sync, but a secure syncing system for free.
Arstechnica has an excellent overview of it and it’s features.
It’s too bad it is doesn’t have higher bit encryption and you have to get your key to whomever you are syncing to by some method other than e-mail to keep it secure, but still a very cool idea.