splashingpixels.com on "[Plugin: WooCommerce - excelling eCommerce] woocomerce 2, tabs"

You're correct, tabs are now manipulated with filter hooks. So you would need this instead.

add_filter( 'woocommerce_product_tabs', 'add_my_tab' );

function add_my_tab( $tabs ) {
// add my tab to existing tabs here.
}