I have updated openSUSE 11.3 with the KDE4 factory and Kate 3.5 does not highlight Python code (beyond the general highlighting), this seems to be a bug with the openSuse packages since Fedora with KDE 4.5 and Kate 3.5 gives me highlighting.
I hope there is a solution since I need highlighting 
Generally you would need a language syntax package for the language you want to colorize. Might check that.
Well I can’t find any packages searching for ‘python’ which contain highlighting, and I didn’t need it for Fedora or for kate in KDE 4.4.
Maybe need to report this in bugzilla.
I don’t know kate well but must text editors with Highlight/colorization of syntax require a script or config file of some sort to define the syntax to highlight for a given language. I guess this is missing. But you are using factory which by definition maybe incomplete. In any case you should tell the problem to the developers via bugzilla. No one here can do anything about it.