Plus if you're already familiar with OSSO or OAM 10g you probably already know what their cookies look like. So for the purposes of this post I'm only going talk about OAM 11g Server and the 11g WebGate cookies when you do an "HTML form" style login.
Basically if you want the contents Eric's post in pretty pictures and simplified down to include only the 11g cookies then this post is for you!
Here's a very simple diagram of the communication between the user, one OAM Server, one WebGate and one Application:
Note: In this diagram I've separated out the WebGate and the Application, though in reality the WebGate is plugged into the OHS Server and the app could be something as simple as a .CGI running in the same server. I've also shown the user talking directly to the OAM Server; in the real world this interaction would likely be through an OHS server with mod_wl installed.