Jon Arnold has an interesting article over on TMCnet about harnessing VoIP going forward. The problem with VoIP applications have always been that they has only really served to replace other voice applications: Vonage replacing your home line, IP-PBX's replacing older PBX's, etc. Unique features that actually caught on have been few and far between.
The article describes efforts by Mobivox and Jajah to take VoIP and use it for something new. In the case of Mobivox, it is for hands free cell phone use (not just talking) while driving but potentially for other applications, for Jajah it is for automatic translation services. However in both cases, the key is letting users talk to their data and applications, finding ways to interface with information that don't currently exist. No replacement here, just added value. No idea if these particular ideas will make it anywhere, but the article is definitely worth a read.