Messenger Plus! Live 4.80 has left the Public Beta state and is now available for free download. It features full compatibility with Windows Live Messenger 2009, including scripts and skins.
Free Download: Messenger Plus! Live 4.80.356 (4.80 MB)
For those of you interested, here are the most important parts of the changelog:

This version is entirely compatible with [...]

None of the existing skins is currently compatible with this Messenger version. However for your convenience I have updated an existing Patch Skin (Skin Patch?) named “Plus!Patch”. It features

Removing sign-in window links
Removing advertisements in chat window and contact list
Removing e-mail- and other buttons in the contact list toolbar
Removing the yellow information bar in both contact [...]

Maybe you’re one of the people who can’t live without music. And maybe you know Deezer, where you can listen to music for free, streamed. How can you show what is currently playing there, in your Current Media info in Windows Live Messenger? To set it up, follow this how-to.

Long awaited, often asked for: the public beta of Messenger Plus! Live 4.79, introducing complete compatibility with the newest Windows Live Messenger 2009 beta.

What is new/changed?

Fresh out of the oven and still pretty hot: Messenger Plus! on WLM 2009. Soon to be released as a public beta, here you can have a peek at what Plus! will look like when hooked into the recent Windows Live Messenger 2009 Wave 3 beta.
Contact List

In the header area of your contact list, [...]