I got DropBox and Ubuntu One. I guess it's a little inconvenient to use both rather than having the best of both worlds sync'd into one folder, but at least there's competition!
Dropbox allows me to share files between Ubuntu and my XP virtual machine. This also allows me to share files with other windeuce machines, which is quite convenient.
Ubuntu-One is Ubuntu-focused, so it's probably great for sync'ing multiple Ubuntu machines (sync Evilution mail, etc.). That's quite awesome, especially when I'll get my netbook just before Karmic's release.
I'm really glad to see the competition between these applications, this should make for rapid innovation!