I have been giving some thought to making the process of creating maps form OpenStreetMap data easier. The problem is that to use the mapnik map renderer, you need to install quite a lot of tools and set different configuration files before you can even start to create a map.
This means you have to be pretty keen to persevere enough to get to an end result.
I am thinking of creating a service to allow you to bypass the tool installing bits, and concentrate on the setting up of the map configuration, so you can get to a result quicker - see http://wiki.openstreetmap.org/wiki/User:Grahamjones#Speciality%20Maps.
Quite a few of the responses that I got to that proposal were about the lack of good documentation to get people started on the process. I have had a go at addressing this by putting together a simple overview presentation to go through the main concepts and tools that you need to generate a map using mapnik. The presentation is on slideshare.net, and should be visible below: