User blog comment:Dopp/Message Wall Now Available in Labs/@comment-3136913-20120128150503/@comment-10370-20120128185714

You can type in a Message Wall post, and it'll sign with your signature, same as everywhere else. You don't really need to have the timestamp in your signature anymore, so you can type three tildes instead of four. People might start using it for other stuff than just a link to your profile -- a picture, a quote, how they're feeling today, whatever. I'm interested to see what the signature-loving folks do, now that you're freed from the need to use a timestamp.

This is a really new feature, and we're still adding and tweaking. It's possible for us to add some customization to the top level signature too -- we want to see what people want, once you've been using it for a minute. Let us know!