Finally, a build of the Windows Live Essentials Wave 4 has been leaked! Unfortunately, Microsoft has limited the use of the applications to certain beta testers, so you cant use all of the different applications. Thankfully, a patch has been created to allow users to use the new Windows Live Messenger (links are the end of the article).
Features including the different views in Messenger (social, expanded contacts and a more familiar view of the contact list) are up and running, though features such as Facebook Chat are not. Other things such as the not-saving-your-conversation-display-picture-sizes bug has been fixed, while other things still require a bit of work (mainly padding here and there).
Obviously, third party addons such as Plus! or A-Patch are not compatible yet, and this program may or may not reflect the final product. As promised, you can download the full installer here and the Messenger patch here to get it up and running.