Peapod depends on very few external packages but just to make sure here is the complete list. While peapod has primarily been developed on linux it should work on any unix-like operating system.

Required
Python 2.4 or above. It may well work with Python 2.2 but it’s never been tested.
Urlgrabber Version 2.9.6 is reccomended. Earlier versions may cause problems. Available on most linux distributions as a package called python-urlgrabber. This does the hard work of downloading files.
PyXML This is bundled with the python install on most systems but occasionally you may have to download it.
Optional
eyeD3 a python package for manipulation ID3 tags. Without this you obviously don’t get ID3 tag re-writing.
Bittorrent 4.0 or above. Required if you want to get podcasts via bittorrent.
vorbis-tools for Ogg tag re-writing. Usually just an “apt-get install” or “yum install” away.
libgpod for ipod support. You need to build the python bindings for this. Debian/Ubuntu users can apt-get python-libgpod.