I use a mix of forbid and special "armories". I have a custom stockpile of steel and rock weapons (obsidian swords) in a room with a door. I have another stockpile of silver weapons in a room with a door. The silver weapon armory is closer to the rest of the fortress than the steel, so new migrant recruits will go there to pick stuff up without my forbidding access to the steel room generally anyway. Forbidding a single door's access is still really fast and easy though.
Then when I want them to switch weapons I set them to unarmed, forbid their weapon once they drop it, lock the silver armory, and set them back to armed and they go to the steel armory and grab a new weapon. Then I unlock the silver armory, reclaim their weapon, and someone hauls it off into the room and stockpiles it. There's no need to station them in the individual armories that I've seen though.
If you wanted to do it en masse you could just set all the dwarfs to unarmed at the same time, lock the silver armory, and designate forbid the entire barracks and meeting area. That might be a little faster than using the stocks menu, but then you might also miss a dwarf or two drinking or eating.
This is basically the "old method" with a little forbid tweaking mixed in and minus the stationing, but it works really well for me. If you use the stocks menu then you don't know what weapons your forbidding and what weapons you aren't, which is fine if your going to field your entire military but if you want to let the latest immigrant dabbling weapon skill dwarfs keep sparring you'll about have to micro manage something like this.
Personally I only have a few dwarfs in good enough gear and with enough skill to take on the goblins in open field anyway, everyone else is still too high a risk of death or severe injury. I find that well placed high quality parts ballistas behind fortifications along the map edges where the goblins show up, a long with a stockpile of ballista ammo next to them and a highly experienced siege operator or two, is probably the best way of dealing with them though.
[ December 11, 2007: Message edited by: Durnheist ]