Lync 2010 Mobile Client
Coming this fall Microsoft is set to release the official Lync mobile client. The plan as it stands now is to release clients for Android, iOS and Windows Phone 7. The client will support IM, presence and VoIP based calling. The VoIP based calls will allow users to make VoIP calls from their mobile devices and allow the call to appear from their main number. Users will also be able join Lync based online meetings from their mobile devices via email and calendar entries.
Best of all, the traffic will be fully encrypted and secure. Some screenshots are available online. I highly suggest taking a look. Below is the a link to a site featuring screenshots of the Lync client for Windows Phone 7.