The ruby on rails podcast is the only podcast I am currently listening. The show is always pretty good with lots of interesting projects and questions. For example the interview with the seaside developer was great. So the latest podcast with Sean Chittenden was something special because he is the one behind the new Penny Arcade backend (former php now rails powered). He answers a lot of interesting questions regarding: Apache webservers and fastcgi, Open source licenses, MySQL vs. PostgreSQL. Highly recommendable.