The big blue download now button on the
download page will give you version 4.70.334, which is the last non-beta version, but this version is not compatible with Live Messenger 2009 yet.
A little
below the big blue download button you'll see the text
"Users of Windows Live Messenger 2009: download the latest compatible version of Messenger Plus! Live here (in beta)". That link will give you version 4.79.0.353 which is compatible with Live Messenger 2009, but still in beta. As long as Patchou thinks the new version is not 100% stable yet it will stay in beta and not replace the main download yet to avoid crashing computers of all users. Having that said, the new version seems to be pretty stable... if you do encounter problems please report them in the bugs forum
.