This is mainly an advertising stunt. The State of Geneva has been promoting an evoting (internet) system for the past 6 years. They complain that citizens are not interested in the voting process, but every time computer scientists (mainly free software advocates) have indicated that they had doubts about the system (but noone except the State has access to the system), the criticisms were treated with disdain (to say the least !). Some background information about the system is at http://www.geneve.ch/evoting/english/welcome.asp (it does not talk about the criticisms, though).

Now, obviously, they can not link every citizen's computer with the central voting server with a quantum-encrypted link; here, they are just encrypting a 500 meters internal link between two servers of the State. This election does not use evoting; however, this is part of a general policy of showing "see, we do the best that's available, so our system is secure" -- they don't care about the fact that with evoting, the weakest link is the individual citizen's computer. Instead, they use quantum cryptography to protect an already secure link -- already secure, because votes are tabulated in the first center, so they get the results out from there on paper as well, which is pretty hard to hack...