this is the wrong forum for the question since it does not involve code or custom development.
to answer your question - the presenance information is relying on either Messanger or live communication server (LCS). different web parts may implement the code that shows the current status of the person in the messaging software.
The descision of which web part to use is up to you - depending on the need you have - who do you want to display. Every sharepoint list can have columns of type person that supports showing the online status of the person chosen. so you dont have to use colleague tracker - you can use any sharepoint list.