Please read the article at OMG!Ubuntu linked under the picture for details.
This is a great idea; it condenses down the top bar, and makes it easier to log into chat.
I also second getting rid of the “post to” section. Partly because I never saw a reason for it. I mean, I go right to gwibber and type my message there. Having too many places to type messages is confusing for users.
I don’t use it to set IM status, but it makes sense to set status from the messaging menu rather than the me menu. I might actually use this to set status; I can see how it’d be handy when empathy is on a differnet desktop.
I also like the idea of hiding it. Some people don’t want the envelope there because it doesn’t fit with their workflow; they should be able to hide it without having to completely remove the message menu via the package manager.