It's funny how these trends change. Once upon a time, a one column layout would have been boring, and we all ran to frames to give us columns. I guess I'm just old-timer enough now to start seeing the changes.
Single column only works on a single page/article/concept being shared. Beyond that, it gets a bit silly to get from point a to b, but there are times when multiple columns still work.
Maybe when I'm done with reading, I like to check out related links on the side. I'd rather not scroll all the way to the bottom to do that. Or if I run an ad, I want to make sure the placement (though still outside the main body of the article to not be distracting) is still at prime real-estate.
Do X for a better Y is always tricky business. It's sometimes not as simple as one column.
Probably indicative of a larger trend too, as the web continues to intrude into all walks of life, we'll see a scaling back on all sorts of levels. Things like the Slow Web movement emerging (whatever happened to them?)
Boring is good in some contexts. In this case conversion rate optimisation. No distractions allowing you to focus on the call to action.