Small correction: there's a fairly low limit to how many volumes you can attach to an EC2 instance. Available storage is very high, but not "theoretically unlimited".
You get /dev/sd[b-p][1-15] as mountable EBS volumes. Thats (15 * 15) * 1TB, or about 225TB. You may even be able to go higher than "p", but I haven't tried. I'm also not sure, you may even be able to attach somewhere other than /dev/sd* .
Either way, after that, your EBS bill is $22,500/mo, just for storage, so you might be able to figure something else out for that cost.
But you CAN attach that to a $14/mo EC2 instance, which was my original point.
In my experience a volume can only be attached to /dev/sd[b-p], so it's a 15TB limit per instance. If what you say is true, that would be great news. I'm testing it right now.
Also, in response to your question: I can confirm that EC2 complains if you try going above sdp, or anywhere else.
I know that the Centos and Ubuntu AMIs don't know anything above /dev/sdp, but I haven't tried any others. I have tried /dev/sd1 through /dev/sdd15 and /dev/sde1-4, and that works fine on Canonical's official 10.04 AMI.
