I keep hearing rumors over twitter and elsewhere about Adobe having a project called Pacifica. It's supposed to be a Flash based platform which will have a SIP stack embedded inside. That means handsets with faster user interfaces, more compact and powerful processors may not be as necessary as some.
It also is a great boon to client Vringo and their video ringtones market because converting video into Flash is easy, then layering it into the call set up and tear down becomes a no-brainer. That means quite simply that Vringo can be in front of and after the call with all kinds of cool content, and the concept of ads, offers, updates all delivered to your handset becomes simpler.