I need to send push notifications to an app that will be on both iOS and Android. GCM now allows the ability to send push notifications to both platforms. Does PushSharp support this, since it supports sending messages directly to GCM?
Short answer, yes.
Basically you need to specify slightly different payload for GCM on iOS notifications, and this is outlined in google's documentation https://developers.google.com/cloud-messaging/http-server-ref#downstream-http-messages-json
PushSharp supports both the old Data and the new Notification payload types.