[Plugin: Google XML Sitemaps] error on line 2 at column 1: Extra content at the end of the document

in /wp-includes/query.php change this

// Always sanitize
		foreach ( $this->posts as $i => $post ) {
			$this->posts[$i] = sanitize_post( $post, 'raw' );
		}

to

// Sanitize before caching so it'll only get done once
		for ( $i = 0; $i < $this->post_count; $i++ ) {
			$this->posts[$i] = sanitize_post($this->posts[$i], 'raw');
		}

Poor hack I know!

Try the new beta:

http://downloads.wordpress.org/plugin/google-sitemap-generator.4.0b8.zip