Missing icons in notification area on Natty

If you, like me, are using Dropbox, the Dropbox Icon will not show up in the Notification area on Natty. To solve this, see http://www.omgubuntu.co.uk/2011/03/how-to-hide-or-show-app-tray-applets-in-ubuntu-11-04/

Short version;

To see the current value type:

gsettings get com.canonical.Unity.Panel systray-whitelist

You should get something like:  ['JavaEmbeddedFrame', 'Wine', 'Skype']

Now, add Dropbox to the list:

gsettings set com.canonical.Unity.Panel systray-whitelist "['JavaEmbeddedFrame', 'Wine', 'Skype', 'Dropbox']"

and at the next login you should see the Dropbox Icon.