In the current version of the WYSIWYG in the Magento admin interface, if any of the new HTML 5 elements are used, they are stripped out. This simple module adds compatibility with all new elements.
This module follows Magento coding best practices and so is upgrade proof.
A succinct list of the new elements can be found on O’Reilly’s site
To download the module please visit the module’s page on Magento Connect