http://www.gainax.co.jp/anime/gurren-lagann/chara.html
According to Gainax's website, every character except for Simon, Yoko, Viral and Old Coco now have surnames. Though, their surnames are just the names of the villages (or in Nia's case, the beastman's former capital). Though this isn't that bad, as we learned that the Black Brethren came from a village called "Bachika".