The federation of Exchange with UIUC has been completed.
We should be able to start seeing calendar free/busy and Lync availability information for UIUC folks now.
This was just implemented, it may take some time for things to show up on our side. It is not showing up for me yet at the time of this writing, however.
P.S. We have been federated with the UIC campus previously, and this should not be affected.