Conferences like Mobile World Congress are typically exciting times. Details of glitzy product launches and demos fill websites and newspapers with promises of a better tomorrow. While the world watches Barcelona, though, groups are taking the opportunity to highlight other causes. Public transport workers, for example, are striking this week in the city, causing widespread disruption. It's an effective bargaining chip for those upset with their contracts, as attendees at the world's largest mobile conference have seen simple 10-minute subway journeys turn into two-hour traffic jams.