Been using mod_python for a while, I read more and more articles about how good WSGI is, without really understanding why.
So why should I switch to it? What are the benefits? Is it hard, and is the learning curve worth it?
For developing sophisticated web applications in Python, you would probably use a more comprehensive web development framework like DJango, Zope, Turbogears etc. As an application developer, you don't have to worry about WSGI much. All you have to be aware about is that these frameworks support WSGI. The WSGI allows separation of web server and web application code and a system administrator can change the web server as long as the web application is WSGI compliant. If you are developing in one of these frameworks, you would anyway be satisfying this condition. 
If you are a web framework developer (that is developing DJango or Zope itself), then you have to understand WSGI in more depth.
Why should I use WSGI?