In the PS2 dating sime game YUMERIA, NENEKO is wearing that same hat.
http://www.yumeria.com/chr/neneko/index.html
and her hat has something special...
http://data.yumeria.com/chr/neneko/m...neneko_adv.mpg
YUMERIA is scheduled to air in January.
In the anime, the hat design will be changed a little.
http://anime.powerbean.jp/yumeria/chara/neneko.html