Thanks Arnaudt, Khujo and Bunnios again for this latest leak from Redmond, It"s MSN Messenger 5 this time at build 5.0.0327.
MSN Messenger is a direct response to the court ruling to seperate MSN Messenger from Windows XP. The Windows XP version is not much different than the standalone version for all Windows versions only the name is "Windows Messenger" the rest in the later builds (from 4.6 up for XP) is the same including the pesky ad"s which were left out of the shipping versions of XP.
MSN Messenger 5 brings more of the .NET into Messenger and a newer visual GUI of which I think looks like it"s escaped from Longhorn/Blackcomb concept skins. While Longhorn and Blackcomb aren"t real (yet) this is.
UPDATE: Thanks brn2prgrm for a link to the fix :)