What could be the ideal server side stack for an iOS two-player game?

I am about to start an iOS two-player game. Its a card game, and is played turn by turn.

After going through a lot of articles and blog posts, I have decided to go with these:

node.JS on the backend to respond to API calls. MongoDB as the database. and Apples Notification service to push data to other devices.

I am comfortable with JavaScript and I am willing to learn node and mongoDB both and I have some time before the project can start.

I have worked with PHP and Java in the past.

Considering the entire scenario, shall I go ahead with what I have thought or there are things I should consider.

You can also consider google app engine using a java or a python backend as the server side. The most obvious advantage is that you wont have to worry about infrastructure hassles as GAE is a managed service. GAE has a high replication datastore similar to mongo and you can code the backend in java which you already know.