If you are looking for a guild on the 2 main servers here is a link to the active guilds with info about them and links to the websites.

Xeth Guild Listing: http://forums.station.sony.com/vg/posts/list.m?topic_id=44001

Seradon Guild Listing: http://forums.station.sony.com/vg/posts/list.m?topic_id=52555

You can also ingame go to your social window "O" then Guild tab and LFM tab.  It lists the guilds recruiting but is it out of date so look for players on in the guild you are interested.

Good luck with your guild search.