In the case of FASTCGI this usually means mod_fastcgi or mod_fcgid under Apache, and although many web hosting companies do use these modules and so can provide support for Python, they often don't, or the support provided is less than ideal.
In taking the view that support for Python isn't very good, one does have to be careful however. This is because when you read support forums and irc channels, you obviously are only going to see the complaints and the calls for help to get things working. It may well be the case that this is an outspoken minority and the bulk of people are having no problem at all. Either way, there is still a perception that the Python community isn't being well serviced by web hosting companies and that something better is required.
As I have previously described in the mod_wsgi roadmap, the intention is to support features that would allow mod_wsgi to be used in mass virtual hosting, but there is a lot more to it than just providing yet another option that they might be able to use. In fact, there is no real reason why good Python web hosting couldn't be offered using FASTCGI right now.
I tend to think that the real problem is in part one of education. That is, lack of good documentation on how to setup FASTCGI for running Python within a commercial web hosting operation, and a clear indication of what the Python communities expectations are as to what should be available.
Some of the problems which arise are web hosting companies that provide only woefully out of date Python versions, no easy ability to install Python modules/packages, and in the case of FASTCGI, not even providing flup or some other FASTCGI bridge. End result is that although one may be able to use Python, it isn't necessarily easy and a lot of the hard work is pushed onto the user, rather than the web hosting company providing an environment which is easy to use to begin with.
With that in mind I am currently contemplating whether to start up a distinct uber project which has the specific goal of improving commercial Python/WSGI hosting options. This would not be done with the intent of just pushing my separate mod_wsgi software, but would look at all available software and come up with guidelines and other documentation on how best to use whatever is available, including CGI and FASTCGI.
I can also see this going beyond just documentation, with it also producing code libraries and applications. For example, at the moment for someone to host a Python WSGI web application under CGI they need to know about what CGI/WSGI adapters are available. Similarly for FASTCGI you need to know about what FASTCGI/WSGI adapters are are available. That or you need for the Python web application being used to internally somehow support CGI or FASTCGI directly.
Frankly, with WSGI, these days it is pretty stupid for Python web applications themselves to be worried about CGI or FASTCGI. At the same time, the user also should not have to need to know about them either. What would be much better is that no matter what underlying Python hosting mechanism is used, that the web hosting company provide a means of hosting WSGI applications themselves.
As example, when using mod_wsgi all you need to do is provide a WSGI script file which contains an 'application' object as entry point for the WSGI application. That WSGI script can also include any other code required to set up the environment for the WSGI application. There is no reason why this couldn't also be applied to CGI and FASTCGI.
So, instead of a user having to provide a .cgi or .fcgi file, they would provide a .wsgi file. It would then be up to the web hosting company to automatically ensure that the right thing happens.
Obviously, web hosting companies are going to be clueless as how to make that work and this is where one product of the project would be to provide a small set of Python wrapper applications which perform that mapping along with the instructions on how a web hosting company would integrate that into their systems. This would therefore need to include guidelines on how to set up Apache, including how to integrate it into suexec or cgiwrap as appropriate.
One of the problems that this wrapper application can solve is fixing up WSGI variables like SCRIPT_NAME and PATH_INFO. At the moment Python web applications often have hacks in them, or the user themselves are forced to have hacks in the WSGI script file, to adjust these variables where they aren't passed through correctly from the web server.
Another problem than that can be solved here is ensuring that logging from Python web applications ends up somewhere where the user can actually see and make use of it. One often sees instances where people are having trouble with something like FASTCGI, but due to how the system is set up, any error messages output when the FASTCGI script is being started disappear, making it really hard to debug problems. Because the wrapper application is in control of loading the WSGI script file, it can ensure that any log files are setup properly. It could even provide a feature to capture the errors and return them in a error page to the browser rather than them going to the log only.
So, that is the dream. In part I need to indirectly do some of the ground work for this in order to work out what features I need to add to make mod_wsgi more useful in a mass virtual hosting setup. It would be nice though if there are others out there who have some measure of passion for seeing Python web hosting options improved contribute as well. Most of all, I would dearly like to get the web hosting companies themselves directly involved.
In respect of dealing with web hosting companies, to date my experiences in dealing with them have not been very inspiring. Where I have actively tried to contact them to try and learn how they run things, so I can work out what features mod_wsgi should provide to make it easy for them to use, they have been quite unwilling to give up any information. Even when web hosting companies have contacted me about mod_wsgi, it seems the contact is coming from managers or sales people and not the technical people. Even at the requests of these same people, their own technical people aren't necessarily forthcoming with the information I really need. Overall it has been quite frustrating to say the least.
Hopefully then if this project were to get off the ground and were seen to have active backing from the Python community, we might be able to make some progress. We may even be able to make web hosting companies see that there is more than just PHP out there.
Right now any feedback you may want to give on the whole idea and whether there is a need for it would be most helpful. Maybe I am barking up the wrong tree and all is actually wonderful after all. As much as I may believe there is a problem here needing to be solved, am sure that existing mod_wsgi users would prefer I concentrate on just mod_wsgi and not worry about all this other stuff. :-)