I'd like the Magnus' solution: I don't like to be automatically redirected to the Italian subdomain, because I'm working (even if only occasionally) on the Swahili one, and I'm interested to the Esperanto version, too. So according to the Magnus' idea I would have the IT (my HTTP setting) highlighted, but with the other languages at hand.
This is not a great problem. One could have in preferences the best wiki for him/her. Note i don't say that the jack's solution is better than the magnus' one. But the option for select the first wiki should exist for any solution adopted by wikipedia (since maybe active users could prefer enter direct into wiki without passing by portal).
-Riba.