A key issue that my customers have raised is that if they send a Lync meeting request to their customers/partners who don’t have Lync, then can their customers/partners join via a mobile device. Prior to October 3, the answer was no. They could only join via the Lync web client.
On October 3, Microsoft released an enhancement that allows people (customers/partners) who don’t have Lync to join on their mobile client (Windows Phone, iPhone, iPad) as a guest. This is AWESOME since most of my customers have one of these mobiles devices and now they can join Lync meetings from them.
Another key feature released as part of this update is the ability to start an unscheduled multi-party Lync Meeting from your mobile devices. See this post for more details