Have you ever read an article full of typos and grammar mistakes and questioned its legitimacy? As you spend a few hours setting up your educational Myspace page amidst thousands of other users who have spent years learning the culture and etiquette you should realize you are not the leader of this pack. Your youthful mistakes distract from the message you bring in the same way typos distract from what you read. This is not to say that you shouldn't try. Rather it is a reminder that the most efficient way to get a message out to a population is to use someone from that population spread the word.
If one of your employees loves participating in MySpace, Facebook, Second Life, or some other possible new media conduit, use that love and energy to do what you can't. That person who is familiar with the method, excited about the message, and motivated by having fun at work can quickly do something you may never be able to do--earn the respect of a target audience, and then teach them something new.
As for yourself...learn and participate, but don't kid yourself into thinking you're gonna be an instant expert.