Comment 5 for bug 610416

Yes, teams spread across multiple time zones.
A single event will probably not spread across multiple time zones, even by the same team.. (i.e. a team has a global jam event in one city, and another one in another city that are two different time zones, it is also two different events.
Yes, the organizer should specify the time zone (but this should actually be done by venue, just like the location and the languages can be set for a team, the time zone should be set for a venue.. a venues time zone is not going to change.)