The only issue is that a lot of programs (mobile apps, especially) seem to interact directly with the Dropbox API, which leaves no possible interface for a seco

The only issue is that a lot of programs (mobile apps, especially) seem to interact directly with the Dropbox API, which leaves no possible interface for a secondary authentication. Google gets around this by having app-specific passwords that you can generate and de-authenticate at will; it'll be interesting to see how Dropbox handles it.