Software is becomming the platform of choice for Unified Communications. PBX's are transforming from proprietary silod platforms to software application running on servers. The big players in this space are Micrososft, IBM and Cisco (in addition the the PBX vendors own offerings). Cisco has taken the "acquire" approach, while Microsoft and IBM are developing mostly internerally. The big challenge today is the convergence to the corporate IP network. Voice and video have unique requirements for bandwidth, and most companies are re-engineering their networks to address these new needs. Microsoft's technology is a bit trickeir since bandwidth consumption is adaptive.
Most companies are evaluating options or traffic prioritization. QOS is the most common technique. Though QOS does not guarantee a quality experience, it certainly can help network managers prioritize traffic, especially on WAN links that are already saturated.
Though we're in tough economic times, UC is still popular as businesses are looking to reduce communications costs. Audio conferencing and Web Conferencing are hard cost savings which have sparked interest of late. Businesses will still have to spend money to save money.