Yahoo messenger 18.104.22.1686 has been released but yet again yahoo have not provided yahoo messenger full setup offline standalone installer.
Rather if you go to download yahoo messenger from yahoo messenger official site you will get a web based installer for yahoo messenger which will download and install yahoo messenger from internet on run time.
With web installer for yahoo messenger you will not be able to install it on any other computer which is not connected to internet.
If you want to download yahoo messenger full setup standalone offline installer which is portable and make it easy to install on any computer irrespective of its internet connectivity.
These are some links to download yahoo messenger full setup standalone offline installer as per different languages.