This summer Meebo intern Kevin Irish created a technique to communicate between cross-domain iframes in IE7. This effectively makes postMessage universally available for use today. The Meebo Bar already uses it in production (for 150,000,000+ users / month).<p>He has intended to write a blog post explaining how it works, but hasn't had time. Upvote and comment on this thread to encourage him to write the post, so that everyone can benefit from his research and implementation!