Some CMSs that are used in the newsrooms have a liveblogging interface built into them but I know of ones that come without such a feature. So, while I was updating my list of liveblogging tools I came across a nifty way of using Google Docs for just this very purpose.
The folks at Google have been refining Docs a lot so I don’t know if this technique still works – but for its simplicity, I am yet to come across something better. It essentially involves the use of the ‘republish’ feature of Docs to keep a blog updated with a series of posts. Of course, you shouldn’t look for additional features here – but with sharing enabled, I think it can be pretty useful.
Blogger Amit Agarwal has described it in detail in this post on the Google Docs blog – here’s an outline to get you interested – create a new document; input content; save it; republish it as a new blog post; keep the “Automatically re-publish when changes are made” option checked; open a new browser tab; input content; save; republish and so on…

And now for the other tools that could be used for liveblogging.
CoveritLive – comes in Basic and Premium versions, the latter one with an ad-supported option. Without branding and integration within your pages, it can look a bit conspicuous.
ScribbleLive – also has trial and paid versions in different categories. Plenty of features.
Qik – for live video blogging. Has versions for the iPhone and Android-based mobile phones.
Ustream – also for live video broadcast. Has different versions for both mobile and tablet platforms.
Audioboo – for audio. The Guardian uses it on its blogs.
Storify – Tool to curate and feature social media inputs on a page.
