As you probably know, Dropbox recently graduated to the big 1.0. Now, Dropbox is supposed to update to newer versions automatically. Mine, however, did not for some reason. You can see which version of Dropbox you have installed on each of your linked computers in the My Computers section of your online account. Just point your mouse at the "i" next to each computer.
If you see that you're still on a pre-1.0 version, you can update manually using these steps:
- Quit Dropbox on your Mac
- Wait a bit for everything to really quit
- Download the latest version.
- Install in the usual Mac fashion
(via Shawn Blanc)