I recently witnessed a complete end to end demonstration of Microsoft Unified Communications via Exchange 2007 and OCS(Office Communicator Server 2007) and I must say that it is impressive.
If you look past the bucket of CALs (client access licenses) you will need to purchase in order to implement such a solution, it really does provide a great arrangement of applications.
The list includes (but isn't limited to):
Email
Instant Messaging
Presence Management
Voice over IP calls (whether it is within a managed VoIP optimised network or across 'standard' internet services)
Video Conferencing
When this type of communication system is then combined with a smart phone running Windows Mobile 5.0 or 6.0 linked to the network, the presence of a person can be viewed no matter where this person may be.
In addition, Live Meeting is another feature of OCS solution. For those familiar with WebEx, you'll understand what Live Meeting can do, but it goes one step further by allowing a mixture of voice and video participants.
Now, where does all of this wizardy help? Well, its incredibly beneficial with businesses who either have a number of remote workers (or looking to allow more workers to work remotley) and those workers that are constantly mobile such as sales agents, consultants, support people etc.
This is made possible due to the increasing availability of good quality cost effective cabled and wireless internet connections using 3G and DSL and the development of voice codecs that help to utilise the available bandwidth much more efficiently in order to make and receive good quality telephone calls.
The other positive with such a solution is that its quite scalable. To obtain most of the benefits mentioned above, requires 1 server running Exchange 2007 & 1 server running OCS 2007. However, if your solutiuon calls for high-availability, the number of servers will increase to provide redundancy as does the complexity of the solutuion.
Accepting the server licensing and the potential number of servers, its well worth considering..