In-game bad manners are, unfortunately, often part and parcel of the whole PvP thing. I'd like to say that too many people think that mannerly play is somehow unmanly play... but that would be make a gender-specific reference and I would never do that. *ahem* I think that we need to improve our filter for offensive words, so that people are disinclined to swear and name-call. And I think that as players we may need to develop a bit of a tough hide to let the insults of the poopie people roll off our backs. Lastly, I think we need to continue to try, continue to model good behavior. Never, ever sink to their level; always, always show the best that you can, and hopefully another player or another guild will rise to your high levels.
As to the community as a whole, and social aspects of the game, I wanted to toss in a couple of ideas, too:
All of our BWE guests are very intent on getting as much gaming into a weekend as they possibly can. There just doesn't feel as if there is time to be sociable because people want to take on another quest, go do a bit more PvP (not PK, silly, PvP!

) or run through a mission. I believe that when the game is out, we'll see a real switch to a more relaxed and sociable atmosphere. People won't feel they are "wasting time" by being in town; that will be part of the game experience.
I also believe that having chat filters -- which I know we will have at some point -- will help. When you can filter chat to remove, say, all the emotes, you will see a lot more chat and a lot less dancing, and waving, and all the other fun things that people enjoy doing with their characters.
When we institute the full in-game trade system, I think that we'll all see less trade spamming. I don't know what is coming on that or how it will be handled, but the designers know that a system is needed and they're clever people -- they'll nail it.
Lastly, a game takes time to mature, and so does the community. My first real online game was Diablo. I went online and it scared me to death!

Scrolling chat, people using pretty awful language, aggressive smack talking. My innocent eyes had never seen such a thing. I was, literally, in a panic to get out of the chat room and into the game. "Hurry up, hurry up!" I was thinking as I closed my eyes and jumped out of chat.
Well, I "stayed a while and listened" one day. (Sorry, wrong edition, but you'll appreciate a good insider reference.

) I found amongst all the chatter a few thoughtful individuals trying to carry on a conversation. I found a few quite interesting, and yes, it wasn't easy, but it got better. Within a few weeks, more nice folks appeared, and we got to such a number that we started our own in-game "discipline." It involved such things as "This is our room, please don't talk like that." We couldn't ban people, as I recall we couldn't mute people, but with time, the nasty folks just stopped coming around. Diablo Retail USA-1 was ours. I met one of my favourite people in the world in that channel, and we're friends to this day.
I fully anticipate that this will happen in Guild Wars. Groups of people will find that they naturally gravitate to like people, and that those of us (and I am one) who enjoy the social exchanges nearly as much as the game itself will find that we end up in, say, Ascalon City 3, or Lion's Arch 12, or places like that. It will take time, but we will
have time, and with that, we'll find and be in the places we most want to be.