Google released a Google Labs project that replaced the Google search tabs with images that expanded similarly to how OSX does in their dock. Google quickly pulled the project, most likely because it was too successful for a Google Labs project, but you can still find the Google Blog post here
and a screenshot here
.

"I started working on a version of my own. Mine works more like the OSX dock but it isn’t perfect". You can find it at shiwej.com/googlex
.

Mirrors of Google’s project: here
and here
.

Thanks to Jason Schramm Shiwej