You got some good points there.
MS indeed rarely shows version numbers, and you're not the only one who finds this extremely annoying. (You wouldn't believe how much bandwith I sometimes waste just to discover I already have a particular version, etc)
It has been not so long that MS finally decided to post version numbers in their Download Center (though, not everwhere).
eg (WLM 8.5.1302.1018):
http://www.microsoft.com/downloads/details.aspx?F...-b445-0487bd5e84ef
But it has to be noted... Since WLM is now installed via the Windows Live Installer, this also means (I think) that you again could well end up with a different version being installed than it was advertised on the download page. This because you now actually download an Installer which on its turn downloads the setup package. :/
Anyways, as for WLM. If you download from the official site
http://get.live.com/messenger/overview (or sites which link to there) you will always have the latest public version, whatever it might be...
If some sites tell you that WLM 8.5.XXXX.XXXX is the latest version then:
a) either it is, and you would be able to download it also from the official main site (see above).
b) it is a private beta version which got leaked.
c) it is a fake version, a mockup of somebody (no telling if it would do harm or not)
d) the sites are simply wrong. And they all say the same number because in this world many sites copy stuff from the other sites. Information is quite often
stolen from eachother (and often without verifying anything)...
bottom line: always download from the official site
/ 
