The following comments should perhaps be viewed in the context that I'm an experienced computer consultant but very new to the blogging scene.
My thoughts on the blog-as-extension-of-CV idea would be that, as someone who has run quite a few interviews, what you want is something in a common format where you can quickly compare like with like. The trouble with the blogs that I've seen is that they're all a bit "stream of consciousness" in flavour: I find myself following links to things I'd never thought of and, after some time, coming away not really knowing what I've learned or indeed what I hoped to find out in the first place!
The "serendipity" that this can create (in terms of finding links to stuff you hadn't thought of) is potentially of great value - but I'm not sure it's the best thing for objective comparison of candidates, especially in what tends to be an uncomfortably accelerated time frame.
If only blogs followed a slightly more predictable format whilst retaining their inventive content... or perhaps I'm missing the point.
Feel free to lampoon a Luddite - but one who, perhaps, is not so unlike a large portion of web users...