What driver should I say to Debian that my Mac Mini needs?
This bug has been reported and supposedly fixed. There is also a patch available. Link to the report and thread on debian bugtraq: http://lists.debian.org/debian-kernel/2010/10/msg00453.html
an updated package is already in launchpad
try using the regular install CD instead of netinst(it should have a newer kernel)
if you must use netinst, I'm thinking it will require rebuilding the iso with the new patched driver/replaced kernel