App Store download/installation status?
From Check Download Progress on the Mac App Store:


  How to See Download Progress of Apps Coming from the Mac App Store
  
  Want a general idea of an app downloads progress? Here’s what to do:
  
  
  From the Mac App Store, click on the “Purchases” tab to see the active list
  Locate the app(s) you are downloading that you want to check
  


Also if Launchpad is in your Dock it typically shows some information too.