So, when you used to add comments in NewsBruiser, you could enter a URL for your website, as is the norm. I was usually lazy and didn’t bother typing the http:// part at the beginning, though– still worked fine when you clicked on it.
Unfortunately, the conversion to WP has apparently treated all those URLs as relative… which might be technically correct in other contexts, but doesn’t really make sense in this one. Anyway, the upshot is that if you click on my name in a comment I’ve made to any pre-WP entry on your blog or mine, you’ll probably get directed to http://that-page’s-url/blogs.gnome.org/calum, which obviously doesn’t exist. D’oh.