I would add another point to the last post on why Blogs are Popular with Search Engines and comment that it is not only page structure that works well but often overall site structure. The fact that many blog systems like Word Press and Moveable Type allow bloggers to categorize their posts can actually help Search Engines spider blogs and give them authority.
I get quite a few hits to the category pages of my blogs. For instance, one of the more popular entry pages from search engines on this blog is my Adsense page. This is not because loads of people directly link to this page (I can only find one external link that does) but it is because that particular page is keyword rich (ie the word Adsense is all over it ) – not because I’ve rigged it that way but just because its in virtually every title and first sentence of each post. It is also a page that is linked to from every page on this blog in the menu.
One of the disadvantages that I see with Blogger blogs (without hacking them) is that they do naturally come with a categories option. Instead posts are only archived according to date which means that they miss some of the benefits outlined here.