Where is the Tomboy panel applet?

I'm making the assumption you are running the Unity Interface - if you are using the classic Gnome interface then the following doesnt apply to you.

In Unity, all the previous Gnome Panel applets will not work - except if they were Application Indicators. Unity doesnt allow you to "right click" and add to Panel anymore.

If you start Tom-Boy from the Dash (click the top left 'circle of friends' icon and search from Tom) you should hopefully see the new Tom-Boy Application Indicator displayed in the top-left of the screen.

Add Tom-Boy to the "Startup Applications" so that the Application Indicator is started when you next login.

Just running Tomboy should load it in the indicator area (it's not an old applet so it doesn't show up in that right click menu anymore):

Tomboy is not anymore a panel applet (you won't find it in "Add to Panel"), but it will provide an applet in the Indicator area once launched (ALT+F2 "tomboy").

So, if you need the new tomboy applet to be loaded automatically in the Indicator area, you'll need to go to "System/Preferences/Startup Applications" and then "Add", Name: "Tomboy", Command: "tomboy".

This applies to Gnome Desktop AND Unity.

This full solution was already provided in previous answer, but was spread into several answer and comments.