Found the following post on the dropbox forums, so two things to try (I can confirm it is working on my computer with nautilus-dropbox 0.6.8-1).
1) Downgrade to nautilus-dropbox 0.6.8-1 if running a newer version.
2) Try running the following commands if on the newer version:
sudo ln -s /usr/lib/nautilus/extensions-2.0/libnautilus-dropbox.a /usr/lib/nautilus/extensions-3.0/libnautilus-dropbox.a
sudo ln -s /usr/lib/nautilus/extensions-2.0/libnautilus-dropbox.la /usr/lib/nautilus/extensions-3.0/libnautilus-dropbox.la
sudo ln -s /usr/lib/nautilus/extensions-2.0/libnautilus-dropbox.so /usr/lib/nautilus/extensions-3.0/libnautilus-dropbox.so