This module adds the option of displaying search facets as tabs. It's heavily
based on the "links" widget that comes with FacetAPI, and has just altered the
rendering rules of the links, as well as added the "All" tab.
Simply activate the module, and you can select the Tabs option from your facet
configuration form. You'll probably want to move the tab facet block to a
different region (top of the page) than the other facets (commonly in a
sidebar). Some CSS work will also be required to style the tabs.