I'm rapidly becoming skeptical of the opportunity for enterprise "unified communications" -basically a glorified term for combining telephony, IM, email and collaboration. It seems to work on the misguided premise that somehow businesses can coerce their employees to use a single, centrally-managed communications hub.
Maybe in really proscriptive organisations it might work - government departments, or industries in which employees are so fearful of their jobs they'll put up with whatever the IT department foists on them. And for companies' departments which are wholly dependent on teamwork, some of the functionality may get used, some of the time.
But the idea that it will stop employees running their own parallel communications channels in nonsense. Generally, there's always something on the Internet, or on personal mobile devices, that is newer, more intuitive, and most importantly, which their semi-professional friends and "network" also use. The threat that "you can't install it on company laptops" is irrelevant if everyone's got a decent browser-enabled personal mobile as well. And the threat that the company won't reimburse users for non-approved forms of communication (eg personal mobiles where the user "owns" the number etc) also loses teeth in the face of flatrate phone calls and data tariffs.
And then there's the fact that most UC platforms don't integrate many employees' favoured forms of communication - SMS, Skype, even MySpace or other social networking platforms.
I'll come back to this theme another time, but for now, I'd sum up by saying that for every form of communications "unified" in a central managed platform, another two unmanaged (and more user-friendly) ones will inevitably spring up to take its place. This all fits into the general mythology around one number / one device / one identity, which, as I've commented before, is and utterly falacious philosophy.