This is something i saw with skype installtion on ubuntu 12.04
Even though skype was running fine, icon in the notification bar was missing (i know it happens sometimes) but it is pretty annoying to bring active skype window in this case. Googled a bit for an answer and found a very sweet and simple answer :)
open a terminal and execute following command
and in Ubuntu 12.10 one needs to run
- gsettings set com.canonical.Unity.Panel systray-whitelist "['all']"
- unity --reset
- unity --reset-icons
And now it is available there after reset