Well, Pixie got sorting fixed in the current release. Unfortunately, [posts:here sort=updated] considers that a comment is an update. So if you set sort=updated in your Entry template, when anybody comments on a post the whole thing gets bumped to the top.
Now, this isn't necessarily a bad thing. Popular posts would get bumped up top, which means that more users will see posts that are relevant to interests. It also means that users will be more likely to see which posts are being commented on, which allows them to quickly identify interesting conversations.
However this isn't generally expected behavior in a blarg . Its more common for the behavior of a forum or an image board. Posts with high activity stay up top; boring shit fades away. Blogs are more controlled than that; it is generally accepted that the blarg owner controls posts and their position. A blarg post usually isn't bumped to the top unless the blarg owner wishes to bump it.
So the question is whether or not I want this behavior. The answer is that, for now, I don't. I don't want total control over everything on this blarg , but I also don't want to run a forum site. So its out for the time being.