While sitting in a giant conference call (the kind that wastes 1h30 times tens of participants' time), I realized that it would have been infinitely better had the organizers placed all the information and files on a blog beforehand for the participants to scan it according to their centers of interest. People speak at 100 to 150 words per minute (and a lot less than that in international calls when speaking in a foreign language) but they read ten times faster. We could have easily saved 2/3 of the conference, make it only 30 min for questions and answers only. Having people standing on the phone listening (and/or falling asleep, doing their emails, surfing, blogging ;-)...) as others read their speeches is plain wrong, a waste of time and money. Live telephone calls should be used for live conversations. Blogging in this case also brings some other benefits such as saving a history, making it easier on notes taking (no need for a formal report of the call, just drop interesting things as comments or update the posts if necessary) and, last but not least, expose under the sun a lot of valuable content that would otherwise be trapped into invitees emails and call participants heads (granted, sometimes it's good to say rather than write certain things, however that should be an exception, not the norm of conference calls).
Speaking of emails, it is obvious that blogs can help prevent information to be trapped into "one-to-happy-few" email exchanges ("François, do you have this email from Philippe with the latest reorg? I can't find it.") or help diminish the traffic clogging the network pipes (like those 10MB newsletters or travel catalogues that are sent to the entire company by someone who could just blog them). There are many small groups in an organization that could really benefit from a simple publication system rather than making email even worse than it already is, yet they are forced to use email because only a couple of overworked people can publish on the official intranet site.
I also can confirm from first-hand experience that blogs can be a nice complement to tools such as Microsoft SharePoint which are easily misused, when served by the IT department as the do-it-all-collaborative solution for everything. I can imagine that SharePoint is a fine product for IT project management, but it didn't compare favorably to a simple blog as a collaborative tool in a training I've been following recently. SharePoint is an Office-centric, document repository with a forum. But when there's a timeline, the need for free form posting (I didn't find how to post anything else than a file in SharePoint) and for a conversation with context (think of the comments as a powerful tool to add context for people outside of the team, reading the blog as a report or digging for more information), blogs are simpler and cheaper tools. And I absolutely can't stand a tool that has no notion of permalink!
Those are just a few examples of improvements that blogs can bring on the intranet. They're small, but they are quick wins considering the small investment and low barrier of blogs. As with email when it started to enter into corporate culture, they require awareness and changes in habits and it will take time for companies (the bigger, the longer) to realize how they can best fit them into their existing communication tools.