Amy Gahran discusses how blogs might actually hinder conversations in Blogs as a Barrier to Conversation. She writes:

Not everyone has the technical abilities, equipment, and access to use the internet much (or well). Not to mention that using the internet at all requires literacy and available time.

... and later:

Although weblogs get a lot of attention currently, I think it's important to recognize -- and respect -- the spectrum of options and tastes.

I'd propose that it might be conversation through written word (as opposed to in person, voice or video) that might be at fault here, aside from the technological issues that blogs present. There's a reason why smilies are used in e-mail and IM messages... it's near impossible to add inflection in plain text. There's a reason why some novelists are successful and many are not... crafting effective meaning through written word takes time and talent. Add to this the fact that technology makes it all too easy (or even encourages) users to fire off text without giving ideas the full thought they deserve, exasperating miscommunication even more.

I'm not saying that we all need to be novelists to carry on a conversations on-line, but the problem of the many-to-many conversation might never be possible to solve due to our own physical limitations rather than technology's limitations. For example, try getting your message across during a crowded family gathering or at a town hall meeting where you're fighting with others to be heard and everyone has their own agenda.

With the audience so large, and as Amy points out, with many people stretched for time or constrained by literacy issues, on-line conversations might only ever be effective for a small part of the population. We'll see how things pan out over the next decade. Maybe I should add some new features to the conversational-media system I was envisioning... features that would allow everyone to participate regardless of their literacy or financial standings and technology skill levels.