Update 5/1/15 - On a different instance of Mongo, I had run the command noted below and got errors. However, this worked:
mongoimport --db mean-dev -c points --file "points.geojson" --jsonArray
Let me save you the hours lost in trying to figure out getting GeoJSON features into individual documents in a collection versus one document with nested features.
MongoDB 3.0.2. Valid GeoJSON file full of 809 features.
Using this code:
mongoimport --db test --type json --file ./'mobilemaps.geojson'