can somebody tell me the best practices for sending push notifications to millions of devices?

I am using nodejs+mongodb as backend. I wish to send push notifications to Android and IOS devices.On each user actions the notifications are send to his/her followers. The app has pretty good number of users and app's current installs is more tan 3 million.

I have done it before on ASP.net platform to limited number of devices.But when considering a large scale i'm pretty skeptic.

Do i need to implement any type of queuing?

Do i need to use Redis for this purpose?If yes for where?

Somebody plz suggest some nice libraries which might be helpful for me.

Thanks in advance

via M14