#jsonp

This is not really new. This is just an example of the same DOM/JS garbage collection issues that have plagued webdev since time immemorial. Don't keep references to DOM nodes in your JS code: they tend to stick around.

"This page should show you your twitter info if you're logged in."

"If you pass callback=CALLBACK to a del.icio.us JSON feed it will now output proper JSONP that does not set the Delicious.posts variable (easy to fix in your callback function) but calls CALLBACK with the JSON object as a parameter."