I think ..

Getting readers involved in discussions is one of the prime objectives for a blogger. And for this blogs have the comments section which has a huge significance as far as blogs are concerned. The comment section gives the power to express the reader's opinion, and gives blogger an idea of the popularity too. This is in desynchronised mode.

But .. There are almost no alternatives to live chats as it is a synchronous casual text-based conversation between two or more individuals.

All users will go directly to that room and chat about your blog post. Since Geesee is cross-site chat, anybody chatting in Geesee on any other site can search for tags and easily find your blog post room and join it and chat with others.
Say I have a blog post like .. Microsoft’s new mp3 player – Zune.

Why will they chat about "my post" instead of discussing about "Zune" in a good forum that predominantly discusses about Microsoft products? Instead if the post is like .. Top web2.0 loosers, readers may get involved in conversations as you talked about.

To conclude I like the idea to some extent. But if would have offered me something like skypecasts I would have raised my both hands!

Thanks