I had this idea, but turns out that CoveritLive does exactly the same thing and they have implemented it beautifully!
The current blogging tools usually fall short when trying to put up a liveblogging / running commentary post. The blogging software itself is supposed to be a reverse chronological listing of posts. Now when writing a live blog post of an event that the blogger is covering, what is usually needed is chronological listing of the news. (So its like an inverted blog within a post!). Mostly, people manage their own timestamps and formatting for the liveblogging post. This tends to be tedious and a distraction from the real event that one is trying to cover. Instead, CoveritLive is a great tool that handles all this for you!
The cool thing is that it also has features that support multiple authors, uploading media and rich formatting. Its a great idea and a fulfills a surprisingly obvious need. I think I am gonna use this for the next liveblogging event I cover. Do check it out!