Well http://mostexclusivewebsite.com/ currently has 46,000 users concurrently connected, in-line, receiving live updates, waiting for a ticket. So yeah, I would go so far as to say that Meteor can be scaled pretty well.
I've just tried to access the site and it's failing to load half the time, and the other half it's taking over a minute to load. It's awesome you're getting traffic but I'm not sure you can say you've successfully scaled your app right at the moment.