Hub, Song, Lizzy, Louis, and I looked at the Magic the Gathering community for the assignment, and I focused on social norms within the group.
I interviewed two of my friends who are in the community; one is a player who has been playing for 15 years and takes part in local tournaments but follows the national tournaments, while the other is a moderator for one of the larger forums. Both were incredibly enthusiastic and helpful (thanks Jack and Captain!), and I learned a lot.
Magic the Gathering has two different settings: online and in person. In person interaction involves gameplay at many levels, from casual play with friends to the tournaments. Online, players either take part in the forums or play the game but mostly lean towards discussions there.
Players all have different motivations - some are interested in the cards themselves on an art or interaction level, some the storylines of Magic. Many are interested in achievements and winning though, but the game designers keep all in mind when building their cards so that everyone can be included. This is also important at the tournament level; the statistic I got was that women make up about 43% of the total community and yet only 15% of the tournament sub-community.
To keep gameplay fair, players generally play with other players of the same skill level. That's not to say that they don't ever play with newcomers; the community is pretty open to all people and willing to teach (though the forums can have less open minded people), but this is more in the casual play arena.
There's a code of conduct within the forums and the tournaments that enforces players to be courteous to each other in order to keep gameplay fun and inclusive. At the tournament level, matches end with a handshake for example, and no one is allowed to 'backseat play'. Any misconduct is handled by moderators or other authoritative figures; though players can report problems, the punishment and monitoring is ultimately handled by these figures. Punishments range anywhere from warnings to bans from tournaments for up to years depending on the severity of the infraction and the setting.
Though you can play Magic online, the community's online presence seems to be more tied to the forums. Here members can talk about anything related to Magic so long as they do it within the right topic thread. There are threads where players can discuss things tangential to Magic, such as which pop culture figures belong in which color, but they're kept separate from spoiler discussions or other game related threads.
We even played a round of Magic ourselves (thanks to Hub and Song for teaching me how to play!), and ran into some of the norms: Hub as the veteran knew all the latest rules and pointed them out to Song and Lizzy, who were experienced but hadn't played in a while. I as the total newcomer had to be taught all of the mechanics from scratch. Hub and Song helped me learn by looking at my cards, but generally no one else looked at anyone else's cards.
Learning about the community was a great deal of fun, and if the members generally are anything like Hub it's a great community to be a part of.