I updated to 12.04 from 10.04, and had problems with sound. Now the sound works but I can't add icons to the top panel. I've tried all these and they don't have any effect:
You can't manually add items (e.g application launchers or widgets) to the Unity panel.
To remove the battery icon you can either remove the package indicator-power, run gsettings set com.canonical.indicator.power icon-policy 'never' in a Terminal or use Unsettings and set "Panel" -> "Show battery status" to "Never".
gsettings set com.canonical.indicator.power icon-policy 'never'
You can't change the user menu icon.
You can use unity-tweak-tool for some tweaking (Removing the battery or bluetooth indicators, for instance), but you can not add new launchers or indicators, I'm afraid...
I'm not sure if this is a bug or by design. I just recently installed a clean 11.10 (well, preserving my old home partition from 10.10).
For the icons in the upper right (for me, Dropbox, Sound, Network-Manager, etc), I need to click AND HOLD all these icons in order to keep them open. For example to log out, I click the "power" icon and when I release, the menu goes away. I have to press, hold, and then release on the "log out" item.
If this is a bug, how can I help file? If this is configurable, how do I configure it? I'm not sure what the default experience should be.
This does appear to be a bug, I've seen the same behavior myself intermittently. I don't see any currently open bugs that appear to be related to this, so I'd suggesting going ahead and filing against unity-2d for the time being and see if someone has suggestions for how to provide more information when the bug is triaged.