Pictures folders shared with your contacts and you have flickr etc. A shared music folder and spotify/grooveshark etc?
Basically an infrastructure company in the most elemental and violently grand sense of the word?
(a) I love this sentence, and (b) this is probably why people are so excited about Dropbox, myself included.
But, the potential of a company is not equal to the potential of its product category (unless it's a monopoly that lasts for all time).
Considering that Dropbox is the one company that has just "made it work", I wouldn't be so sure of that. Syncing isn't always easy and at scale the problems are that much bigger. Mix in cross platform issues (not just Mac/Windows, but mobile too) and it gets that much more interesting.
You're absolutely right that syncing is a classically hard problem that Dropbox has addressed impressively well for consumers.
#1: Dropbox.
#2: http://www.eye.fi/ , which my mother uses to get photos on Facebook despite having no understanding of the file system metaphor.
Personally, I use Dropbox. It's super elegant in terms of the UX for my girlfriend. I take photos, drop them in my Dropbox folder, and send her an email. She makes with the clickyclicky on the magic blue bit. Bam, vacation photos. We both managed to screw things up, frequently, when I was trying to send her photos on Flickr without opening them to the entire Internet. Dropbox makes it a one-click operation for her, and I can manage drag-and-drop on most days.
Thanks for posting that, I had no idea that any such device had actually made it onto the market!