this is usually how play groups get formed - types of play, and rules followed...
Well... typically - the way you meet people who play Magic is via the internet - at local shops/tourneys, or at pre-releases...
The way it develops on the net is mostly chat, and now MTGO... and even there - you play in certain rooms, and usually dela with people you want to play against - every now and then you hit the tourney freak...
As for local shops - you begin hanging around players in the shop, and groups can form through idea-sharing and play-testing... even going out to eat...
as for the big tourneys - you tend to be in the middle of a mass of people form EVERYWHERE... so when you find someone that may live close to you - you tend to talk to them more, and maybe set up a time to meet/play...
Magic can be brought forth in casual talk/play, but only if something is going on - like you may be working with your cards and someone notices it and takes an interest... or you may be asking for days off to travel for a tourney, and people wonder why, and then get interested...
someitmes - in my case - people get on your system and note your favorites and wonder what the fascination is with all those sites and then get interested...
cards on the work desk are also in my case...