According to this post on the Fresh Prince actor's official Facebook page, Jaden underwent the big chop for his new movie, Life in a Year. His father serves as producer.
A Twitter user uploaded a picture of Jaden with his even shorter hair and it really is quite the change.
But hey, Jaden is the product of Will Smith and Jada Pinkett Smith. No matter what his hair is like, he has got those good genes working for him.