I thought that the idea of an alliance was seamless integration between carriers. That being said, what is the point of adding codeshares to these flights if the carriers booking engines are already programmed to show other star carriers? As the alliances grow, it's starting to get quite ridiculous. For instance, when US joins star they will be the only carrier to fly from Spain to North America. They already have US/JK/UA codes on the flights. No doubt AC will add theirs as well and possibly some of the other star carriers too. This clutters up airport information screens, prolongs boarding announcements, etc, etc.

Perhaps the solution is to have an alliance-wide code and have the operating carrier's name displayed along side that eg ST@1022 Operated by Air Canada.