See A Penumbral Eclipse Of The Moon Today
A full eclipse occurs when the Earth moves completely between the Sun and the Moon, casting a shadow that blocks out the moon. A penumbral eclipse differs in that the Moon only passes through Earth's penumbra, which is basically saying that the shadow is a bit off-center. Rather than a direct cross, the moon is slightly out of line, so Earth does not quite cover it completely.
So today at 2:32pm until 6:53pm you should be able to see a sort of shadow cast across the moon...of course with all the rain today, there's a likely chance we won't see anything. Boo.
If you want to read some fascinating stuff about the mythology surrounding eclipses, Wiki has you covered:
The Incan and Mayan cultures believed that during a lunar eclipse, the moon was being eaten by a jaguar. Fearing that the jaguar would come down and continue eating, they would take weapons and shout at the Moon to keep the jaguar away.
As recently as the nineteenth century, the Chinese navy fired weapons at the moon, believing it was being consumed by a dragon.
And finally my favorite myth - the Mesopotamians believed that an eclipse occurred when seven demons were attacking the Moon. The culture believed that what happened in the sky would happen on land, so they feared that seven demons would attack their king. In order to save the king, an impostor king would pretend to rule. After the eclipse, the fake king was "made to disappear (possibly by poisoning)". What a crappy gig! Pretend to be king in order to save the kingdom, and end up getting poisoned for your effort.