it is for both. at least you can connect to the remote one on *.meteor.com using
meteor mongo myapp.meteor.com
see the help by running
thomas@Thomass-MacBook-Pro ~/> meteor help mongo
Usage: meteor mongo [--url] [site]
Opens a Mongo shell to view or manipulate collections.
If site is specified, this is the hosted Mongo database for the deployed Meteor site.
If no site is specified, this is the current project's local development database. In this case, the current working directory must be a Meteor project directory, and the Meteor application must already be running.
Instead of opening a shell, specifying --url (-U) will return a URL suitable for an external program to connect to the database. For remote databases on deployed applications, the URL is valid for one minute.
--url, -U return a Mongo database URL
see also here ( http://bit.ly/1MZiwkD ).