The 0.0.0.0.1 version of landing page was deployed. It's the opposite of perfect, but that's fine, the very first step is always the hardest because that's an actual innovation, all subsequent steps are just optimizations even if the change the page completely.
I still haven't decided on ways to communicate between different users. Private streams do not need communication, but the fact that a stream can be public implies some form of discussion. I don't want to implement usual comments flow (be it with threads or not). I guess a response style like from twitter could work? In this case the author is still notified and at the same time all the comments still physically reside on the commenter's blog.
One way to go about it would be to allow to create derived messages. It could work as a comment and at the same time enable a number of use cases. E.g. you have a stream with books to read and create a derived messages with a stream with reviews for any book you've read.