When installing a 32bit system with grml-debootstrap 0.55 then the resulting installation lacks presence of a kernel image.
Grml release 2013.02, shipping grml-debootstrap 0.55
Solution: upgrade to grml-debootstrap >=0.56 (available from grml-repos as well as Debian/experimental) via running:
apt-get install grml-debootstrap
Workaround for already installed systems:
apt-get install linux-image-686