The elementary OS daily PPA contains a Dropbox plugin for Pantheon, which seems a little bit outdated but still works fine.
Please don't add elementary-daily-PPA to your sources, it is for testing purposes only and may break your system!
Instead download the plugin and install it manually:
There is a small bug in this package, but luckily we can fix it.
After you installed
pantheon-files-plugin, start pantheon in the terminal:
now take a closer look at the output in the terminal. If you see this error message:
[_LOG_LEVEL_WARN 23:17:33.808365] PluginManager.vala:128: Failed to load module from path '/usr/lib/pantheon-files/plugins/libmarlin-dropbox.so': libmarlincore.so.0: cannot open shared object file: No such file or directory
close all instances of
pantheon files and run this command in the terminal:
sudo ln -s /usr/lib/libpantheon-files-core.so.0 /usr/lib/libmarlincore.so.0
pantheon-files in the terminal again, the error message must be gone now.
Unfortunately the default elementary OS icon theme doesn't provide the necessary emblem icons. I've created some of my own and pushed them to elementary+. After you installed this icon theme (just follow the instructions on their GitHub page), you should see nice overlay icons and have a right click context-menu in your Dropbox folder: