It would seem that the documentation, at least the FAQ page at http://www.open-mpi.org/faq/?category=slurm is a little out of date with respect to running on newer versions of SLURM (I just got things working with version 1.3.3) .
According to the SLURM documentation, srun -A is deperecated, and even if you look in the manpage for salloc, -A is not directly mentioned, it's just discussed in the --no-shell section.
I was able to successfully submit/run using:
salloc -n <# procs> mpirun <exename>
without needing an interactive shell. So doesn't this seem like the more up-to-date way of doing things rather than srun -A? Also, it would seem sbatch replaces srun -b, but I don't use this mode of operation, so I'm not sure.
Perhaps the OpenMPI documentation should be updated accordingly?