Could you make the fans of your favorite team visible?

You can look for supporters of a certain team by using the search bar at the top of every page (make sure you select users from the dropdown). We'll also going to do a proper user directory, but can't say when that will be ready. Also, pretty soon the most active supporters of a given team will be featured on the team's page.

How do you register as a Supporters Group? Is it as simple as making the login the name of the group or will there be a checkbox that will be in the next version that will help distinguish that?

Your default 'group' is set to whatever team you support, in your case Arsenal. Going to the arsenal team page will show 10 or so most active arsenal fans in the featured fans section. To see more, click the More Arsenal Fans link. Alternatively, just type Arsenal into the search bar and select users. You can also search by location, email, name etc.

We'll improve this system in the future, but for now this is absolutely functional and is an easy way to find fellow supporters.