I haven't looked into details of all these plans/blogs. But I do have some thoughts about how I'd go about monetizing Twitter as if I am Twitter's product manager:
First, I'd just forget about conventional online advertising(CPC/CPM).
- people are on twitter to have conversations. If you are an advertiser that only cares about getting people off Twitter and go to your site, you don't really use Twitter's conversation workflow to market. You are working against Twitter users' behavior.