Can anybody clue me in to the wacky green lightning in ROTK?

I know its not out just yet, but the trailers have me puzzled- during many scenes which sem to be immediately before some tremendous battles with Sauron’s forces, there is this great pillar of what looks like green lightning/goo above the army. What is this? I’ve read the book, and don’t really recall Sauron’s armies being lead by a giant pillar of gooey green lightning.

Lemme Guess- Its the ark of the covenant! So THAT’s where the Nazis got the idea! :wink:

A pillar of smoke by day gooey green lightning by night…

http://www.theonering.net/movie/preview/rotk_trailer01_01.html

Could be part of the alarm signal when Frodo and Sam start mixing things up around Cirith Ungol, or else the signal from Barad Dur to start fightin’.