How do I get notified when the Dropbox app is updated? I realized that I was running a very old version of Dropbox for Mac. Somehow I was not notified about the latest updates. I was expecting the same behavior as apps like 1Password.

In the past, I missed out Selective Sync by few months which I was eagerly waiting for. 

I was running 1.1.35 (Under Preferences/ Account) and the latest version is 1.1.43 . 

Where can I find the config to let Dropbox auto-update/prompt me on every release, similar to 1Password.
Try MacDropUpdate.

It's an automatic updater that automatically updates your Dropbox to the latest forum build of Dropbox. Works on OS X Leopard|Snow Leopard|Lion.

Edit: it's also Growl-enabled, so you may get notified whenever Dropbox's been updated.