The GW2 PAX reveal was leaked early by IGN and the video seemed to point to GW2 going F2P. Some people datamined the client and found that it is going F2P but only to level 15. Here's the info that was data mined...
Possibilities (gathered from the strings, obviously could have changed since):
Only one or two character slots
Limit of level 15
Seems like a limit on how high a "rank" you can get (specific to trial or possibly PvP related)
Only able to send mail to friends.
Can't send items or gold through mail
Can't speak in map chat
Can't access Team Arenas
Can't access main WvW maps (EB and Borderlands)
Can't sell items on TP.