The code above seems only to work on the root of the blog. It doesn't add page numbers to Categories. I don't know enough about php to get it to do that.
Matt's site shows page numbers any where there are more than one page. Categories and Searches being the big two that I've noticed. Also if it is page one there is no number. This is something I would like to do.
I tried your plugin but it seems to output as a link. So in the <title> there is a the whole thing in the title bar the unparsed url and along with the page number.