for that earlier post about WvW concerns: (I'm expanding IoJ's post)
Fort Aspenwood: AVTR, uA, SHED, WvW/CREW, DPS, FIST, Daze, UM, FUNZ, EPX (all IoJ)
Jade Quarry: PRX (SoS/SFR), SF (SBI), RG (from EU), RAGE (SBI), Yaki (SBI/SoR- yes, they moved twice), VaL (CD) + 2 other guilds unknown atm
Kaineng: RUN (IoJ)
Northern Shiverpeaks: QQ (IoJ)
Sanctum of Rall: Hel (IoJ), RMA (from SoS), MORD, SYN, NYS, SAHP, DU (all SBI)
Sea of Sorrows: ND (IoJ), VoTF (SFR EU)
Blackgate: LaZy (CD), LW (CD), GoF (CD)
That's what we've seen in about 2-3days. Don't expect the impact on FA to be huge in the grand scheme though, not really a bandwagon destination, just IoJ going there. The biggest impact is SoR and JQ so far.
edit: added 2 guilds since this was made into its own thread, haven't really been keeping up, last I heard Crystal Desert was falling apart as well.