Anything about Ubuntu, Centos, openSuSe and Fedora
Ubuntu 11.04 Missing Indicators or System Tray Items
GMail Notifier and Vuze are some of my mostly used application, and when I upgraded my previously 10.04 to 11.04 system (Ubuntu), I noticed that some of my currently running application that has system tray icon or indicator gone in the Unity side panel and in the system tray area. Googled it and found this link: Ubuntu 11.04 Fix: Show All Icons/Indicators Notification Area.
The quickest way to deal with it is the following:
1. From console:
$> gsettings set com.canonical.Unity.Panel systray-whitelist "['all']"
2. Then refresh the Unity. Press Alt-F2 and type: