OpenSSH 5.1 is out.
OpenSSH fully supports SSH protocol versions 1.3, 1.5 and 2.0. It also includes client and server support for sftp.
A few bug fixes, security fixes and new features come with the new 5.1 release. It’s already released to the mirrors so make sure to get patched. FTP mirrors || HTTP mirrors
Also, if you are interested in the statistics for SSH implementations across the Internet, the graphs below from OpenSSH will surely interest you.
Source: OpenSSH