As we know, in Ubuntu12.10, the user interface is Unity, it is really not so conveience to use.
For example, when i installed the skype, i found i can NOT see the skype icon in the notification bar in the top of the desktop.
After googling for a while, at last i find and success to find it back.
In your terminal, run as:
gsettings set com.canonical.Unity.Panel systray-whitelist "['JavaEmbeddedFrame', 'Wine', 'Update-notifier', 'Skype']"
Have fun with Ubuntu!