Twenty Twelve: Google fonts enqueue.

gistfile1.php

/**
 * An Example of how Twenty Twelve Enqueues a Google font.
 *
 * This is interesting because it allows translators to disable the font
 * as well as conditionally load subsets.
 */
function test_theme_enqueue_opensans() {

	/* translators: If there are characters in your language that are not supported
	   by Open Sans, translate this to 'off'. Do not translate into your own language. */
	if ( 'off' !== _x( 'on', 'Open Sans font: on or off', 'twentytwelve' ) ) {
		$subsets = 'latin,latin-ext';

		/* translators: To add an additional Open Sans character subset specific to your language, translate
		   this to 'greek', 'cyrillic' or 'vietnamese'. Do not translate into your own language. */
		$subset = _x( 'no-subset', 'Open Sans font: add new subset (greek, cyrillic, vietnamese)', 'twentytwelve' );

		if ( 'cyrillic' == $subset )
			$subsets .= ',cyrillic,cyrillic-ext';
		elseif ( 'greek' == $subset )
			$subsets .= ',greek,greek-ext';
		elseif ( 'vietnamese' == $subset )
			$subsets .= ',vietnamese';

		$protocol = is_ssl() ? 'https' : 'http';
		$query_args = array(
			'family' => 'Open+Sans:400italic,700italic,400,700',
			'subset' => $subsets,
		);
		wp_enqueue_style( 'twentytwelve-fonts', add_query_arg( $query_args, "$protocol://fonts.googleapis.com/css" ), array(), null );
	}
}
add_action( 'wp_enqueue_scripts', 'twentytwelve_scripts_styles' );