Yes, this bit of advertising can be confusing, but it's not actually a lie.
When Fearless came out, the ads said it was Jet Li in his last Martial Arts Epic
, not film. It was the last Wuxia (Crouching Tiger, etc) film that he would do, not the last film. He's now going more for action films rather than the martial arts fantasy films.
Here's a pretty good wikipedia writeup about the Wuxia genre: http://en.wikipedia.org/wiki/Wuxia