I am interested in learning about CUMC and have several questions here:
1) CUMC is a end-user application software or can provide lib for engineering to do development?
2) what are the deployment platforms of CUMC server, Unix or windows?
3) what mobile device CUMC can support so far? when it can support BREW?
4) How scalable is one proxy-server pair of Mobile Unified Communication Server?
5) Does the system architecture support hot-upgrade?
Not sure of all questions but here is some information might help you
1) CUCM code is not provided for engineering to do development, you can create apps that work with CUCM but not modify the code by yourself
2) so far there are W2K, W2K3 and linux (redhat distribution)
3) i know some nokia phones are supported, would need to dig about specific models.