On the heels of the race change being implemented, the faction change cooldown has been reduced to three days. This brings it in line with the cooldown time of the race change and server transfers (both at three days).
It's interesting to note the effect all this has: you can now more or less freely move around servers and factions without any major consequences. Three days off of raiding isn't a big deal, however two months off if you land in a bad guild after faction transfering your main is quite an issue.
There hasn't been any blue post about this yet, but the information is present on the screens when you undertake a race change, as pictured above.