I agree with your view of UC as a means to optimize business processes, but that only describes the objective of the technology (the "Why of UC"). It provides the important business justification for supporting end users in their specific roles in a business process. The "How of UC" then becomes important in terms of functionality at the technology level and how it will actually be utiliized. That area is where I think further clarification is needed.

In my view the main "communication problems" that UC is aimed at are in initiating contact with a human being, who may or may not always be "accessible" in all modalities of communication or "available" from a time and priority perspective. Mobile users exemplify the first challenge of selectable accessibility, where a recipient may or may not be able to always talk, listen, read, or type to communicate. Further, it doesn't have to be a particular individual that must be contacted, but any person who is qualified, accessible, and available, as in tradtional customer contact centers.

It goes without saying, the contact initiator doesn't have to be a human being too, but can be any automated business process that needs to notify or deliver important information to a human being. It is also obvious that a business process will be exchanging informational messages, not trying to have a voice conversation with a person. However, message exchanges may be exploit speech if necessary.

The flexibility of UC for communicating with a person should not be limited to selecting one modality of contact for communicating, but must allow for easily and dynamically switching from one modality to another, e.g., asynchronous messaging (text, voice) to instant messaging to conversational voice to mutli-person conferencing. Too many people think UC is only about telephony capabilities via IP telephony or VoIP connectivity, but those are infrastructure and application server considerations that must support what the individual end users really need at the moment.

End user needs should actually be broken down into two functonal categories; their needs for initiating a contact and needs as a recipient of a contact. Obviously, that covers a lot of different functionality that must be kept simple and endpoint-device independent. With all the form-factors and capabilities of new mobile "smart-phones," that is not an easy challenge. However, the mobile user is the one who really needs the flexibility of UC the most!

Jim - in the "big picture", I really don't think it matters exactly how we define UC or what goes into it.  Voice Mail? IP/PBX? Collaboration?  Who cares (except for the vendors who want to be offering "UC products/solutions").  Does the end-user care if they're investing in a UC solution or do they care if they're investing in a solution that has a positive impact on their business in some way?  What good does it do if we end up paralyzing resellers and buyers as they try to figure out if it's UC or not UC?  If the solution, whatever it is, improves a process in my business through better communication of one sort or another - I'm interested! 

Some resellers talk about having a "UC story" to tell their customers.  It's NOT about UC!  It's about improving productivity so a company can do more with fewer people in today's economy.  It's about reducing expenses, increasing profitability, providing better service to customers, meeting the needs of a mobile workforce, and much more.  But it's NOT about UC.

So how do we define UC and what is and isn't a part of UC?  UCStrategies has the definition that describes UC in terms of what it does.  That's more than enough!