IP Telephony segment really did not see much revolution for the last four/five years. Most players have tried to make things simpler, cheaper and some claim that they have the QoS to offer better service. Simpler maybe, cheaper questionable but QoS really not. Service quality has really not improved. I am a Vonage customer for a long time (over six years). I have gone through four different VoIP switch that they have send me over the years from Motorola to Cisco (Linksys). All of them are dumb as a door knob. QoS over the Internet is an end-to-end problem and lots of unification needs to happen within the path of the packet flows for maintaining any kinds of QoS. I use Skype quite a bit and find that even Skype with innovation is codecs (they just released a narrow-band codec with network load feedback within their data-path for improvements in network path). If I used Skype and then do file I/O over my local LAN (I have a LAN with five computers on it) I see jitter and I am not talking about the WAN speed allocations that I or my Skype route having no control over.
Another thing that I am very excited about it the possibilities of presence based routing. Nobody talk about it, probably not working in that direction or even considering that to be a possibilities. This is a very interesting concept and has great applicability. Think about it!