You wish to store server-side information about client agents; this information should follow around users as they browse through the application.
Enable sessions by using the SessionPublisher class instead of the regular Publisher. In your top-level script, simply do:
from quixote.publish import SessionPublisher ... publisher = SessionPublisher()
SessionPublisher uses two auxiliary classes:
SessionManager is a singleton (meaning there's only one instance of it) that's responsible for creating new Sessions and storing them.
Session contains information about the session. Most of its attributes are of little interest to a web application programmer; the single exception is the .user attribute, which you can use to record user information. The data type for .user isn't defined, so you can set it to a string, an instance of your own User class, or whatever you wish. The Dulcinea package includes a User class that you may want to look at.
The standard version of SessionManager stores sessions in a Python dictionary. This means that you must be invoking Quixote through some mechanism that uses long-lived processes; this rules out CGI, but any of FastCGI/SCGI/mod_python will work fine. If you have multiple processes, though, sessions will not be shared between them. For such situations you would have to write a SessionManager subclass that stored sessions in a relational database or disk file.