BlackBerry have announced BES 5.0 SP3 (surely, 5.3?) adds support for OCS 2007 R2 and Lync Server 2010. Get the release notes here, http://docs.blackberry.com/en/admin/deliverables/25751/New_in_this_release_503_1311756_11.jsp.
If you are feeling like you want to give it a go read the documentation here, http://docs.blackberry.com/en/admin/deliverables/25747/Provisioning_BCS_as_a_trusted_application_1396931_11.jsp.
Daniel Noakes