Traditionally, unified messaging is where you let your email system be a place where you access email, faxes, and voicemail.
Despite substantial investments of vendors such as Avaya for some 10 years, unified messaging products have met with little success. Partly, that's because the value of fax integration is, for most organizations, too little. Another, bigger, factor is that the worlds of telephony and email have been separate.
However, existing voicemail systems are now coming to the end of their lives. Customers will have to evaluate new options. Telephony is increasingly seen as an IT function. And high-speed IP connectivity is now becoming ubiquitous. Voice over IP is mainstream, and it's natural to fold in voicemail over IP. So the right conditions for voicemail to integrate with email are probably coming together.
P.S. Our Department-of-Shock-Horror-Titles made up the exciting and innovative heading.
David Ferris, with thanks to Adomo's Andy Feit