the agitation for this originated with a far right political organization, the Egerkinger Kommittee, which used some pretty effective graphic design that did not prominently tie the posters to a particular organization to agitate for the referendum.
there's a pretty good summary of all this stuff here, along with a couple examples of the posters:
Minaret controversy in Switzerland - Wikipedia, the free encyclopedia
this sense of a white christian europe that's been invaded by the Other is a dominant theme in far right/neo-fascist politics. it has obvious correlates in the united states, but here the category neo-fascist doesn't get bandied about (one result is that political viewpoints that would be circumscribed in their appeal were they publicly labelled neo-fascist circulate unmarked)...
it's a bit strange, this referendum.
the depressing thing is that it points to something that one would hope wasn't the case, but which appears to be so: these themes of being-invaded resonate beyond the limits of the electorates who turn out for far right/neo-fascist organizations/parties. 57.5% is a bleak number to have voted for this nonsense.
it's clear enough what this is about as well: controlling how properties are built in this particular way is a device for splitting the Other away from the white christian commonwealth, subjecting them to particular restrictions which follow from this basically paranoid general impression that They are Taking Over (have a look at the poster on the left in the wikipedia article. i don't see how else to read the image of switzerland that's entirely dominated with images of minarets that are done to resemble missles). so it's a symbolic victory for neo-fascists. go switzerland.