Just announced by the Joomla Team is the release of Joomla 3.4.  Also available is Zap Calendar 4.0.20, which addresses some display issues with Joomla 3.4.  You should update Zap Calendar to 4.0.20 (if not already) when you update your sites to Joomla 3.4.

Joomla 3.4 has a couple of cool new features.  The back-end sidebar menu is now collapsible, allowing more screen real estate to pages like Zap Calendar's event, category and location managers.  You can now also edit module settings in the front-end, eliminating the need to switch between front-end and back-end screens when configuring a module.

Also in this release, Joomla has begun the process of removing the standard components from the base release, opting instead to give users the option of installing them after the base install. This will ultimately result in a smaller, faster install for Joomla.  This new behavior is for new sites, so don't worry about components disappearing on your existing sites.  The first component to be removed from the base install is the web links component.  More will follow in future updates.

Zap Calendar 4.0.20 has a couple of cool new features too.  The upcoming events module has been enhanced with 9 module styles and new class attributes, allowing for dozens of display variations.  There are also multiple event download options for several popular calendar programs.  You can read more about these features here.