I just tried the code on my layout and it worked! There was no CSS though so it looked quite plain.

But I'm wondering if we'll be able to disable this feature when we view them? I'm all for having pretty custom profiles and userpic pages, but there are occasions when I'd rather just see the default for the sake of easy reading and clarity. I always liked the option for me to view things in the site style instead of the custom CSS (such as comment pages) without asking the other user to disable it for themselves.