Is this an x64 Scientifix Linux? Have you checked that you have put the image in the correct security group (i.e. ensure that the SSH ports are open)? Sometimes it takes a while for the logs to appear on the Amazon web UI. Perhaps wait 15 or 20 minutes and then have a look.
Ok, I figured out the problem. I included my own rc.local because I needed to do some service specific setup steps. BoxGrinder appends to it. The problem was that the rc.local file on my local box was not executable and BoxGrinder does not ensure that it is executable. Once I added a line in the post section (chmod +x /etc/rc.d/rc.local) to ensure that it is executable, I was able to ssh in.
Thank you for the help. Your comment about the logs clued me in to the fact that rc.local wasn't executing because none of the output was being reported.