Windows Live Essentials 2011 Final is available now, check this out. As reported Windows Live Messenger 2011 Build number is 15.4.3502.922.
Windows Live Essentials 2011 includes Messenger, Photo Gallery, Movie Maker, Mail, Writer, Family Safety, and Windows Live Mesh, plus Bing Bar, Messenger Companion, Microsoft Silverlight, and Outlook Connector Pack (Microsoft Outlook Hotmail Connector and Microsoft Outlook Social Connector Provider for Windows Live Messenger). Operating system requirements: 32- and 64-bit editions of Windows Vista Service Pack 2 with the Platform Update for Windows Vista, or Windows 7, or Windows Server 2008 with Service Pack 2 and the Platform Update for Windows Server 2008, Windows Server 2008 R2.
Direct download link for offline installer http://g.live.com/1rewlive4-all/en/wlsetup-all.exe