The case against blog sidebars
The trail of this thought starts with Matt Gemmell's Designing blogs for readers, which advocates strongly against blog sidebars, and continues with Dr Drang's Blogging and readability, which pushes back against the anti-sidebar sentiments. In the process Dr Drang agrees that blog sidebars only work on relatively wide screens; on the small and narrow screens typical of smartphones (for example), a visible sidebar is a waste of precious space that should be going to the content.
(Apparently smartphone browsers may be smart enough to show only a single column even if the HTML nominally disallows this. For the sake of anyone browsing Wandering Thoughts from such a device, I sure hope that actually works.)
This is the core of the case that I can see against blog sidebars. If how your site appears on smartphones and other constrained displays is important to you, you can't assume that the sidebar is visible; in the best case (with CSS magic), it will appear as a footer instead. If it's going to appear as a footer in some important cases you might as well make it a footer all the time. This at least somewhat unifies the visual appearance and functionality of your site between smartphones and larger displays and means that you only have to design one version of the site's visual appearance instead of two.
(Well, probably not really. You may need to tweak your design for smartphones even if you build it with footers.)
All of this makes me feel conflicted about how Wandering Thoughts looks. Reading Matt Gemmell's article caused me to do a little bit of design tweaking (and to deploy something I've been poking for a while), but WT is still very cluttered. Some of the sidebar clutter can probably be removed (I don't think Atom feeds need to be mentioned any more, for example), but a lot of it has things that I consider important. And some of the clutter exists because the whole blog is actually part of a generic wiki engine and that imposes its own structure on pages.
(I could work out a way to do a total blog-specific design for the blog portions of the wiki, but then I'd have to actually design it. Design is not something I feel I'm good at, which is why the whole of WT generally avoids it.)