The release version of Meteor doesn't include OAuth.
If you're looking for an OAuth client to talk to other login providers
and you're comfortable with pre-release software, see the "auth"
branch on Github. We have an OAuth 2 client implemented there that we
use for login providers like Facebook and Google. It's not merged
into master yet, partly for lack of documentation. But you can
certainly use the existing examples as a starting point for other
providers. And for OAuth 1, see Mike's pull request #251.
I don't know of any current work on an OAuth server for Meteor.