Starting Windows 8, there is the concept of Live Tiles, where applications can present information to the user in the Tile overview. 8.1 also allows "big" tiles, so that further information can be shown.

There are different concepts around this, but what we need to support is basically:

• Number indicator (like for new incoming messages)
• Text display
• Image display
• Updating periodically or depending on application events

http://msdn.microsoft.com/en-us/library/windows/apps/hh779724.aspx
http://msdn.microsoft.com/en-us/library/windows/apps/hh868234.aspx

Native Types of tile notifications:
http://msdn.microsoft.com/en-us/library/windows/apps/hh779725.aspx