Threadthat.com , anybody used it?

What is this threadthat.com ? It looks like something for people that don't want to learn to use PGP and sounds like its just as easy to use as Hotmail. It looks like an easy way to send email messages that are encrypted, but they are not stored in your inbox. It looks like they need your email password to do this? Why do they need your email password? It says it works with any email like gmail, Hotmail, yahoo, etc. So what is the reason for them needing your yahoo password if you want to use it? Anyone know how this works?

Did you ever try it?