Marco's comment from the mailing list:
Actually, the three 'arches' in the logo symbolizes the
Swiss mountains. As 'Clerezza' means 'Clarity' in a local
language (Rumantsch) this is a very reduced link to that.
Why 'Clerezza'? Because using Semantic Web technologies help
us to bring clarity to the massive amount of unstructured and
fast growing web data. It's like in old times when British
people came to Switzerland in order to breathe fresh and clear
air while usually living in a cloud of fog at home.
I also like the idea of 3 bridges - so this logo could be interpreted in many ways