Edit – 20 March 2016
Mongoose now support timestamps for collections.
Please consider the answer of @bobbyz below. Maybe this is what you are looking for.
Original answer
Mongoose supports a Date type (which is basically a timestamp):
time : { type : Date, default: Date.now }
With the above field definition, any time you save a document with an unset time field, Mongoose will fill in this field with the current time.
Source: http://mongoosejs.com/docs/guide.html