Check out my latest article in SharePoint Pro Magazine where I describe how to send push notifications from SharePoint to Windows 8 applications. This same technique may also be used to send push notifications to Windows 8 phone devices, and with a little custom code you can adapt this pattern to send push notifications to any type of device including Android devices, IPhones and iPads
Integrate Windows 8 Applications with SharePoint 2010 and Windows Azure Push Notifications
