A patch has been made available for SharePoint 2013. This patch is known as the March 2013 PU. Separate patches are available for SharePoint Server 2013 and SharePoint 2013 Foundation. This is not a normal CU or service pack.  This patch will need to be applied in order to install any future patches. So, if you install SP2013, this PU should be considered as a part of the base install. Be advised that this PU may be slipstreamed in the install.