I was surprised as well. I got a little scared when I read their email announcement earlier this week where they talked about this license announcement. I fully expected it to be some sort of commercial license due to the lack of information given previously and the polish that even their prototype unfinished product had.

As for the business model, I could possibly see them doing hosting. Although there's no shortage of node.js hosts, they could fine tune their service to work well with the Meteor framework and integrate it in a way that a generic node.js host wouldn't be.