It's not clear to me, either — which is also like Google Wave. I followed links to try to figure it out, but others may not have; why would a special-offer page not at least try to describe what the service is? Not smart marketing.

I just signed up and tried it out with some stuff. It's like a big mashup timeline of all your stuff along with some filters.

So for example I connected my twitter and my github, so if I tweet (or someone tweets @me) it shows up there. Similarly if I commit stuff to github (or presumably if someone on my team commits stuff) it posts the commit message to me.

It's pretty neat, might dig in a bit more later.