Meteor File Uploads

Question

I see that this has been asked here before, but nothing since Meteor.http has been available. I'm still grasping the concepts of Meteor and file uploads are totally eluding me.

Here's my question:
So, in what I believe to be the right method,
Meteor.http.call("POST", url, [options], [asyncCallback])
what do you put for the url? With the client/server javascript relationship in meteor, it doesn't seem like it really uses urls that much.

If anyone has a basic example of a file upload in meteor, that would just be extra awesome.