SSH Agent is a graphical front-end to some of the OpenSSH tools included with Mac OS X. Specifically, it allows you to start an ssh-agent, generate identities, and add identities to an agent.
What's new in SSH Agent X
Conceptually, SSH Agent has changed from a window on the ssh-agent process to a ssh identity manager. This has the following consequences:
ssh identities are no longer treated as documents. Instead, SSH Agent's main window is a view on the identities in your .ssh directory.
Instead of adding identities to the agent, the interface let's you activate identities. Identities can be flagged as Default, and the preferences lets you add the Default identities when the application is launched.
There is an Agent Inspector which shows the details of the ssh-agent process. (It also allows you to detach the application from the process, allowing faceless operation.)
Different preferences format. If you're only trying out 1.1 make sure you backup your nl.uu.phil.* preferences.
Eye candy: An animated bubble showing the number of active identities and more beautiful icons. (Thanks Gerti!)