Techcrunch mentions 3Bubbles. Livechat on your blog using AJAX or some ilk. I don’t think a chat window for a blog post will work. Blogs are still slightly out of synch with realtime and that’s a good thing. It allows people to read, reflect, reflect more, google some thoughts and then make a post. In a way the quality of discourse would go down whereas the quantity of noise would go up.
A chat window on a blog and not a blog post might work but people hit my blog at totally different times and since Google brings so much of my traffic and to posts a few months or years old, what is the point in having a chatroom for these posts? People would need to be sitting on my site all day long for it to be useful.
Here’s a suggestion: Have people agree on one chat channel per topic and have that channel shared between numerous blogs. That might work a tad bit better. This might not be too bad idea for the Irish Bloggersphere with an Irishblogs General chat channel and a IrishBlogs Politics Channel but even at that I think there should be scheduled times where people can drop in and chat about specific topics. Naturally the general chat channel is open 24/7