I also don't think it'd be a great idea. Personally, I prefer written words over speaking on a phone or VOIP conference, because it lets you clarify what you mean without babbling too much... But even with that aside, think of how many members of this forum don't speak english well, and how much worse that would be if we were all speaking instead of typing, where they can at least take their time...
Also, though there are a fair number of us in the US and surrounding areas, the forum is very international, and with time zone differences a lot of people would probably miss out. Granted, those in far-away time zones are probably many of the same ones who don't speak english well anyway, but still...
I'd also worry about 'momentum'... since I imagine many people do what I do, and just drop in, scan for threads, post a bit, and then leave, I'd worry if we'd be able to have enough people online at any one time to actually hold a voice chat, unless the voice chats were scheduled for a certain time in advance.
And, I'm not so sure how suitable the subject matter is to voice chat. A game is one thing, but I can't imagine speaking about a technical topic like electronics without writing or schematics, much like I could imagine an english lecture without writing on the board, but I couldn't imagine an engineering or physics lecture without it.