A slogan seen at pro-Hugo Chávez rallies in Caracas, Venezuela, this week didn't look much like Spanish: ¡Pa'lante Comandante! The apostrophe barely exists in Spanish, and the word pa'lante, as far as I've been able to find, isn't in any standard dictionary.
Nevertheless, pa'lante is a well-understood slang in some Caribbean Spanish-speaking areas and perhaps elsewhere. It's a shortened version of "para adelante," a fairly common phrase made up of the preposition para, often meaning "for," and adelante, an adverb (sometimes functioning as other parts of speech) meaning "forward."
A literal translation of the phrase "¡Pa'lante Comandante!," would be something like "Forward, Commander!" although that doesn't capture the connotation nor the colloquial nature of the phrase very well. (Comandante is a reference to Chávez, the president of Venezuela.) In this context, better translations of pa'lante might be words or phrases such such as "go ahead," "onward," "go for it," "hang in there" or "keep on going."
One related phrase that's widespread is "echado para adelante," so a sentence such as "Estamos echados para adelante" can mean something like "We're all ready to go for it." Sometimes "echado para adelante" is shortened to something like "echao pa'delante." That's obviously not formal Spanish, but it's Spanish nonetheless, the sort you're more likely to see on someone's Facebook page than in a textbook.