iTunes - When adding a free item to a Wish List, an alert reminds you that you can download it right away.
Apple - The image used in the Apple Store for the MacBook Pro subtly shows the anti-glare option of the MacBook Pro with Retina Display.
/via Mario Uher
App Store - When recommending some app from App Store via email, Apple lets you know you are not added to any lists.
Google Chrome (beta channel) - Shows the icons of apps that require internet in grayscale when you don’t have an active internet connection.
Amazon - Changes the categories drop down on the left when you tab down to an autocomplete that is related on the right.
OSX - Excellent integration of the MacApp Store into the OS for unknown file types.
/via Pete Wilkinson
Mac App Store - The progress bar of installing an app from the Mac App Store changes its dimension separate from the icon, when magnified in the dock.