I gave bits of MSC out for people who wrote blog posts, changed their forum signature, or otherwise made some good-faith effort to promote the project. I would suggest continuing the model where you have to at least tweet about MSC to qualify for some.
High powered tweets are still only worth a fraction of one MSC. I'd say someone who has the capacity to produce excellent press release bits which attract the attention of journalists. And still further, for intelligent people to talk to those journalists in a fashion which results in a news story of good quality. If someone manages to a Wall Street Journal writer to cover MSC it should be worth 10 or 20 MSC.
Well, the main goal is to get the MSC into lots of hands, but not for completely free. I didn't (for instance) look at how many followers twitter accounts had. I mostly looked at how much effort the person put out, and how well they understood the project. There's a network effect involved when lots of people participate in something like this. Many of them learn about the project then decide to get involved or buy some, so it's usually worth it on average even if nobody ever sees their tweet.