Even if you don't have a large following on Twitter, for things like this situation, there is almost always a hashtag for the protest in use. For Egypt, it was #jan25, so if you wanted to send a message about Egypt to as many people as possible, you send a message with #jan25 somewhere in it, and people would easily find it, and retweet it to their followers.
Abstractly, in a lot of ways a hashtag on Twitter is like an asynchronous equivalent to an IRC channel, in that you can search for it and get any messages from that tag at any time, and share them with your followers. Hope that helps.