Unified communications is more than just a collection of whiz-bang tools or a hot new technology. Done right, unified communications can help an organization save significant amounts of money while simultaneously streamlining business processes and enabling innovative new communications tools adapted to the needs of the business.
The blade of that sword cuts both ways though. The downside is that merging the traditionally separate voice and data networks exposes each to the risks of the other and creates new vulnerabilities and exploits unique to the merged voice and data infrastructure. Read Voice Convergence Saves Money, Increases Risk for more about the security issues you should be aware of.