Once uninstalled, is data stored by an app on SD card also removed simultaneously? As an example - newer games once downloaded and installed from the Market (Play Store), also subsequently download extra data to a user's SD card. When one opts to uninstall said app/game, is the additional downloaded data also deleted off the SD card?
It depends on where game has downloaded data.

If its under &lt;sdcard_root&gt;/Android/data/&lt;package_name&gt;, the data will be cleared.

If its under some custom directory like &lt;sdcard_root&gt;/GameName/, the data will not be cleared.