I will do an OP here eventually! For now:
The PvE guild is Knights of Arcadia, Defiant, on Faeblight
The PvP guild is The Six Mouths, Defiant, on Sunrest
The EU PvE guild is Planary Arcadia, Defiant, on Argent
When you join the server, type /join PennyArcade to join the chat channel to find someone to invite you.
Bloodycow is running a guardian side PVE guild on Threesprings, called <The Brotherhood>
on Steam and just about everywhere else.