Here is an article in USA Today about a number of phone/voice phishing and other fraud scams. Always interesting to see a general media publication such as USA Today talking about voice security issues. The article lists several types of scams and fraud, but in general, the common theme is calling up consumer or enterprise uses and trying to trick them into giving up personal information. This isn't really anything new, it is just that it is happening more and more. The use of VoIP and UC does make this worse, because the caller can be more anonymous and can easily spoof their caller ID.
One example is the local utility company calling up and threatening to cut off service. If they were to make these calls with a spoofed caller ID of the local utility company, in my case down in San Antonio, "CPS Energy", that would fool a lot of people. Same idea with a cable company, bank, insurance company, on and on. A more clever attacker could also do a little research on Facebook or other social site so they know a little more about the intended target.