Thanks for your attention,
Regards
Hi,
You can currently use the Material Design effect for your web apps, but not in GWD at the moment.
Material Design is based off of the open source Polymer Project, and here is a link with information and documentation:
Polymer Project
http://www.polymer-project.org/
Here is a link to the new Google Design documentation that will give you an idea of how the Material hover effects work.
Google Design
http://www.google.com/design/spec/layout/layout-principles.html#layout-principles-dimensionality
If you know a little CSS you can create the same effect by using the box-shadow property and setting the offset and blur to simulate it.
Pretty cool and hope this helps!
- CN