If you are not familiar with keyutils, it is a library that allows you to securely store sensitive information, directly inside the Linux kernel. You have a reasonable guarantee that the information cannot be retrieved from the memory or swap.
keyutils comes with a binary, keyctl(1), that gives you access to the kernel’s key management facilities. The man page describes the types of available keyrings. The ones the most interesting to the use case I had in mind were the per-thread, per-process and per-session keyrings.
The need for python bindings came when we realized that our release process requires typing the passphrase for signing packages way too many times, so there was a real need for a key agent of some sort. Searching for gpg-agent protocol specifications (or seahorse) returned some information, but nothing I could readily use (I may not have found the proper examples for speaking assuan; the end result was that I could not get anywhere in this direction).
Future versions of Conary will have the ability to read passphrases from the session keyring, if python-keyutils is installed. You can get python-keyutils from either contrib.rpath.org@rpl:2 or foresight.rpath.org@fl:2-devel (depending on whether you need the python 2.4 or python 2.6 version).
Keep in mind that I only implemented the bare minimum I needed for being able to set and get key information. There are other functions the library provides, that could be useful to have. If you find the need for one, let me know; as usual, patches will be cheerfully accepted.