Up to date as of October 16th, 2015.
Once/if you have multiple languages configured on your website, selecting from them for the page becomes an important question. The Drupal 8 language detection and selection options are located the same place they were in Drupal 7 but almost all options got some improvement.
Useful out of the box
Drupal 7 only had the default language detection method turned on, so even if you kept adding in more and more languages (and even if you enabled the language switcher block), the URLs did not work. You still needed to get here and configure the URL detection method. Now this is built-in, so adding languages and placing a selector block would in itself make multiple languages accessible.