Right now I am playing two persistant mods. ORb of Arbrogation with some of my rl friends and Narfell because its so far the "ultimate" in roleplay persistant worlds. I havent been playing very much in Orb, though because the server recently got hacked and my level 9 rogue was among those deleted.
Anyway, I was working towards making a rogue guild on Orb. Not an assassin's guild, (though they would be welcome) a rogue guild. Other than some ideas being tossed around with some other rogues on the server, no real solid progress has been made.
In all, it would be great to get a safehouse guild going, but we'd all have to be playing the same mod. Unless someone builds a safehouse-targeted PW, then it would be kinda hard to make a guild to suit everyone.