It's kind of obvious that Yahoo will gain some type of blogging solution in the future. It's the only major portal not to offer this, as I've written before: MSN's Third Portal To Gain Blogs; Where's The Blog Search?
MovableType's great -- we use it ourselves -- and so would be of interest to anyone who wants to own blogging technology. But the idea Jackson has that Yahoo needs blogs to fuel its pay-per-click growth? Nah.
Google bought Blogger because it was cheap and it figured it could make money but putting its contextual ads out on many of the Blogger sites. But Google later pulled those ads and make them optional. That's wise, because you aren't going to make friends by forcing anyone to carry your ads. So much for needing to own the platform to build ad revenue.
In addition, blogs can be hard to target with ads, given that they often have different types of content mixed onto the same page. MediaPost just had an article looking at this: Blog Ads Hit Rough Patches.
Google's real success with AdSense hasn't been in owning the blogging platform. First, it has signed partnerships with major publishers. Second, it offers an easy-to-use self-serve system that anyone can tap into. Google rolled that out last year, and now you all but stumble over its AdSense placements.
If Yahoo really wanted to turn the web into its billboards, in the way Google does, it would make more sense to have a similar type of paid listings program that any publisher could use.
The downside is that in doing so, advertisers have less control over the targeting of their ads. Kraft wasn't happy to find itself showing up on a pro-white web site recently: Kraft Supports Pro-White Groups? Lack Of Search Ad Targeting Makes It So. Open the flood-gates of self-serve, and problems like this for Google could hit Yahoo as well.
Cory Kleinschmidt over at Traffick takes another swing at the targeting problem in his recent AdSense Faces Extinction -- Unless Google Shakes Things Up post. In it, he points out how uneven targeting is an issue that threatens AdSense. He also notes there are other programs out there to tempt bloggers and other publishers -- which means again, owning the platform doesn't guarantee you the billboard space.
There are good reasons for Yahoo to own a blogging platform, and maybe it will be Six Apart. But the assumption that paid ad placement as a key reason to do so isn't a major factor, from where I sit.