There is the beginning of a list for the Xbox One here:
http://www.cheapassgamer.com/topic/328233-xbox-one-titanfall-gamertag-list-and-gaming-group/
but no one has gotten together yet.. still in the early phases of playing.
I'd love to have an opportunity to test out whether we can play across servers.. right now it seems as if we're splintered across North, South, West and East servers.. but it may be that we can play together, regardless of server. Anyone test that out yet?
if ever there was a game I wish we could cross-play One, 360 and PC, this is it. GRRRR.
I have yet to see anyone at level 48 yet, though I have seen 42.. and I'm guessing 6 of them showed up, as 6 is the max number per team. I'm about level 35, if memory serves, but still have TONS of attachments and mods to unlock for each weapon.. I'm mostly unlocking everything on each one, even if I don't particularly like it (like that first Rifle pilots get.. yuck - and I haven't even touched the sniper yet), then moving onto the next.
Spending way too much time playing at the moment.. it'll even out eventually.