Besides the need for open source lobbyists, the biggest issue with Open Source awareness might be the clique phenomenon, resulting in open source advocates, analysists, customers, developers and users bound to each other. In other words there is also a need for connectors.So... the idea is to launch a campaign to make sure everybody understands what Open Source and Free Software are. A battle for freedom, I guess... A Ribbon to FLOSS (well, that's an idea for convergence...).
Googling around I found a pretty long list of ribbon campaigns - among them the ASCII Ribbon Campaign and the EFF’s Blue Ribbon Campaign - but there is no Free Software or Open Source awareness campaign.
I believe there are more important battles to fight (AIDS, cancer, hunger in Africa...) and I feel my brother might kill me if I start walking around with an open source ribbon (luckily for me, today he is far away in Kenya, fighting hunger). Also, I would prefer to stay away from being associated to battles such as "against HTML mail, vCards and proprietary formats" (that's the ASCII Ribbon Campaign cited by Roberto)... I have the feeling there are more important things in life. Let's all fight for a better world without vCards :-))
Jokes apart, open source is a serious movement and a battle for freedom. It can free your mind and keep big brother at bay, so it is definitely worth fighting for. I am positive on the awareness campaign. Since Roberto's question was "which color would you choose for the ribbon?", I would say: blue, green-white-red or black & white (but I doubt Matt would support the last one...).