i have it enabled on my iphone and i enabled four other people today with MMS. It does work. I just got pictures of my kids swimming from my wife. So I can personally testify that the settings work.
However - you need to update with the .ipcc file first. Then enter the data settings to enable MMS. Then, you MUST change your messaging plan.
Works a treat. I don't know how to prove it to you all, but it really does.