OPs original post seemed to be asking about guild houses rather than captured keeps in wvwvw, regardless of where the thread went. Didn't think his original question was answered.
Nevermind. I'll go sit over there --->
When you made a guild in gw1 you could make a guild hall......a selection of some rly great and very different locations.
Ofc, you can get a temporary keep or castle in WvW.......but he specifically asked about when u create a guild.
Sorry...it just sounded to me like that's what he was asking about.
Squirrel's pretty much spot on - there will be guild halls, while not perchance castles per se, they will serve the same function as a castle for the guild. That the guild owns.