Storing data from blogs and wikis

Insitutional repositories already exist to store abstracts and documents. I was wondering if any of these have a way of storing blog posts or wiki pages and identifying their states; i.e. if a user was looking at a wiki page, they could see and archive edits to find its history.

Whilst wikis do this as the talk page, would you then need to store the edit data differently as drafts inside the repository so that future users can immediately identify the changes and either inspect or ignore them? Would repositories need to develop their own blog search or leverage Google’s BlogSearch and Technorati?