I consider Dropbox, Sugarsync, and the like to be "sync services." Yes, your data are backed up to a "cloud" but you're still using a local copy of the files with all of your various programs.
I consider true "Cloud Services" to be programs that can utilize data straight out of the cloud without having to sync a local copy on your device at all.
I use Dropbox a lot... but only because I want to have the same version of some important files to be available (locally) to several different computers in several locations. The cloud backup is a nice benefit, but it's not anything I really "use." I'll use them for convenience, but I'll never trust one exclusively for backup purposes... no way. Also, the amount of data that I would ever need access to from
anywhere is
infinitesimal. Waaaaay less than 1 Gb—and I prune it constantly.
So my "solution" has been to rid myself of the delusion that there are data important enough for me to need to be in constant contact with it (I'm speaking personally... not from a business POV) .
But in general, I believe that sync, backup, and cloud services are all contributing toward reducing the internet to nothing more than the world's most inefficient switch for the worlds slowest Storage Area Network. Privacy issues not withstanding.