Meteor uses Fibers. And you can do any of the async stuff in Meteor, like you would in Node.js with async.js, with the exception that you will most likely use Futures, and the code style will look synchronous (not the lengthy callback chains we are used to in Node.js). For more on Async execution in Meteor.js, see this link:
https://gist.github.com/possibilities/3443021
Sometimes you have to do a little configuration work to get off the shelf NPM packages settled nicely with Fibers; but its not a huge deal and almost every day someone else will turn npm-somePackage into meteor-somePackage.