I know it's early (very early) days yet, but since we know that our trailer is going to involve a few specific objects (an invisible blob, and the planet Mars I assume) I thought I'd familiarise myself with Mental Ray and some shaders that could be used in the project. First up is a camouflage / cloak effect for the blob.
The shader is a Mia material connected to a ramp for the refraction index, with a Sampler Info plugged into it for the facing ratio. This makes a nice subtle refraction around the edge of the shape.
EDIT: I've scaled the images' width to 500 pixels to fit the blog width. You can view their real size by right clicking and clicking 'View Image' or alternatively 'Copy Image Location', opening a new tab, and pasting the image's URL into the address bar. This way you can see them in higher resolution. (Firefox only)
I'm going to get Alan's help next time we're in Uni to see if there's a way to simulate the Predator's cloaking effect in Maya. Another alternative (when the time comes) is using render layers in Maya and just adding the 'invisibility' effect in post production using After Effects. But for now, tell me what you think of the pics above and if you've got any suggestions of any sort, tell me :)