The issue with Dropbox recently is that for 4 hours, there was no password check. So it's not as much to protect public/shared files, but to protect all files you have on Dropbox, in the eventuality someone gets full access to your account.
My point is that we need something like Dropbox but with local encryption. Putting a TrueCrypt volume on Dropbox isn't a practical solution, IMHO.
I agree as well on the need for an encrypted solution. I'm surprised that Dropbox hasn't been proposing this already. Well, unless they intend to have access to the contents, themselves..
Until that happens, I'm looking for a non-Dropbox alternative for syncing files I would prefer remained private.