I don't know how difficult it is to make a plugin like this. I would like a plugin, that allows people to type and execute commands, when they match a certain requirement. For example: a player that is wielding a fish, can type and execute the '/ninja' command from the spoutninja plugin. Or a player can type and execute a command after he/she has been through a magic gate. This would give much more options to make quests, or storylines. A player has to find the secret ninja hideout and stand on 'the block of the unknown', to be able to become a ninja. (With other words, to have permission to execute the /ninja command.) Again, I don't know how hard it is to make a plugin like this- but it would be a fantastic feature for (rpg) servers. It would give server admins a lot of customization.
I talked to one of the developers, and he told me they will not. They will perhaps allow people to become a certain class under certain conditions, but they will not work with permissions :\