You know Mozilla's email component as Thunderbird, a utility easily integratable as a service extension of Mozilla's Firefox browser.
But no more. Today, the Mozilla Foundation announced Mozilla Messaging, a new open source development initiative incorporating Thunderbird 3. Not merely a new Thunderbird build, but an effort to recast Thunderbird as front and center of a collaborative messaging alternative.
From reading the blog of Mozilla Foundation's Mozilla Messaging's CEO-designate David Ascher today, it sounds as though VoIP integration could be a Mozilla Messaging initiative.
David writes in part (bold face is mine):
It is worthwhile considering what the right user experience could be for someone using multiple email addresses, multiple instant messaging systems, IRC, reading and writing on blogs, using VoIP, SMS, and the like. What parts of those interactions make sense to integrate, and where? I don’t believe that stuffing all of those communication models inside of one application is the right answer. But the walled gardens that we’re faced with today aren’t the right answer either. There is room for innovation and progress here, and we need to facilitate it.
In other words, when it comes to VoIP in Thunderbird- the Mozilla Foundation is thinking about it.