The new update for the Lync metro app is available today for Windows 8.1. Based on user feedback, Microsoft made a number of improvements in this update, here is what is new:
Take control of shared screens or apps During a Lync Meeting with app sharing or screen sharing, take control of the sharing started by someone else in the meeting.
Run Lync side-by-side with another app at any window size Use apps side-by-side when you need to reference another app or website while using Lync. You are not limited to the old 320 pixel snapped size; you can make the Lync window any size you want.
Answer audio and video calls on the lock screen answer audio and video calls quickly when your device is locked, without having to unlock it.
Mute and Control Call Volume from inside Lync Mute the speakers or control the volume of your call from the conversation window without affecting your Windows speaker volume.
In-app contact search Find your contacts faster, with a simple, in-app contact search.
Sign in reliably this update includes a number of improvements to the sign in experience so that you can more easily connect and stay connected.
Windows 8.1 is required to download the updated Lync app.
Source: Lync Team Blog