OpenSSH is a free version of the SSH connectivity tools. It is developed by the OpenBSD Project and in countries that permit cryptography export. It is freely useable and re-useable by everyone under a BSD license.
OpenSSH is developed by two teams. One team does strictly OpenBSD-based development, aiming to produce code that is as clean, simple, and secure as possible. The other team then takes the clean version and makes it portable (being then "less clean") to make it run on many operating systems -- the so-called -p releases (ie "OpenSSH 4.0p1").