Recently after upgrading one Office 365 user from Lync 2010 to Lync 2013, his Outlook 2010 was no longer displaying the "presence" indicators - the little green/red/yellow status bubbles next to people's name.
It seems there can be a variety of different causes and fixes, but in this case, the following information is what helped me out.
First, look at this location in the registry...
It should show this ...
Then, check on the following two entries...
HKEY_CURRENT_USER\Software\IM Providers\Communicator] "ProcessId"=dword:00002458 "UpAndRunning"=dword:00000002
[HKEY_CURRENT_USER\Software\IM Providers\Lync] "ProcessId"=dword:00002458 "UpAndRunning"=dword:00000002
The "UpAndRunning"=dword:00000002 value indicates that this particular IM service is available for use. The system appears to be confused, thinking that both Communicator (the old name for Lync) and the current version of Lync are available. What you need to do is to go to the entry for Communicator and change the dword value to 0.
Now restart Outlook and see if your presence indicators are back.