Since the previous release we have enabled a hidden feature of ARS: its JSON API which allows remote access and manipulation of the repository. You can list, create, edit and delete categories, releases and items using a simple JSON API. At this point in time there is only one experimental implementation which we are using to push out new releases of our own software on our own site. As sson as we consider stable enough we're going to share it with you, allowing the developer among you to benefit from the same rapid release tools we are using ourselves.
Apart from that, this version includes bug fixes for known issues with the 2.0.x releases.
This version requires PHP 5.3 or later. The rationale behind this is explained in our statement of mid-February 2013. It won't install on hosts running PHP 5.2 or earlier.
Unfortunately, due to a long-standing bug in Joomla!'s extensions installer, if your host has PHP 5.2 and you try to install the component on it the installation won't proceed but it will also make the Akeeba Backup icon disappear from the Components menu. You can still access the component by directly visiting its back-end URL, e.g. http://www.example.com/administrator/index.php?option=com_akeeba, or by uninstalling and reinstalling the previous version, losing all your configuration and data.
This is a Joomla! bug, not an issue with our software. There is no workaround. The other alternative would be letting the new version install but not work at all due to the PHP version incompatibility. We urge affected users to file a bug report with the Joomla! project.