The .a file is a partition table. (Magic numbers are helpful.) If you want to extract anything you need to mount it with offsets.
That's easier than using dd.
This is the identity i get:
ai-superjumbo-2011-03.a: x86 boot sector; partition 1: ID=0xc, active, starthead 1, startsector 63, 1493982 sectors; partition 2: ID=0x83, starthead 0, startsector 1494045, 5108670 sectors; partition 3: ID=0x82, starthead 0, startsector 6602715, 996030 sectors, code offset 0x0
Whole partition table right there.
I did this:
Found the offset, which is start sector multiplied by 512. (in this case, use 764951040 as offset. It will give you the second partition, which is storage. The third is swap, and the first is the boot sector.)
I mounted it with offset and loop as options.
I got the contents.
So, here we have some .squashfs files. Same as on a regular live-cd. I guess they're easy to mount and use.
So, yeah. That's all you can do with the image. :P

Look carefully in the partiton. The files are hidden, and the OSs aren't whole. The .overlay folders contain files that are needed for the systems to work.
I also believe that the images are compatible with PowerVR SGXs.
Only thing i haven't found yet is the kernel.

I've made images from them. Ready to use.