Yeah. The Symbol was on a lot of stuff in the bunker as a logo, especially in the storeroom Kate was trapped in. It says "Dharma" on it. And the short and long lines looked to me a lot like I Ching trigrams, but I could be wrong. In fact, it seems that the 8 trigrams are often depicted around a yin-yang, which might be what the wave in the middle is. Maybe it's all a big Korean plot.

And it was definitely on the shark. Maybe it was on the friggin' laser strapped to it's friggin' head, too.