Mozilla launched Firefox 17 officially, and the big news for this release is that Mozilla takes the first step towards social integration by introducing the first revision of Social API and support for Facebook Messenger.
Security has also been improved, by implementing click-to-play blocklisting and “sandbox” attribute (HTML5) for iframes. However, the first feature comes disabled by default.
Additional modifications include performance improvements, with fixes touching on the “new tab” page, repairing the problem with the pointer lock not working in web apps or page down scrolling too far on websites with fixed headers.
Another entry in the release notes refers to the Awesome Bar showing larger icons, but the feature is not available yet. At the moment, the release notes for Firefox 17 are not available on the official download page of the web browser, as the “What’s New” link still points to the details for version 16.0.2.
You can check the full list of fixes on this page.