On the other hand, depending on where you put logic, with HTTP Proxy you can do your testing directly on your server, without Apache in the picture. The fact that it does go over the network also gives you some flexability about distributing your application.
SCGI and FastCGI can go over the network. But yes, HTTP is nice for testing. And so with WSGI you needn't choose one over the other ;)# Ian Bicking