Here's a nicer solution (IMO) using splice:

sub split_into {
   my $howmany = shift;
   my @from = reverse @_;

   my @buckets;
   unshift(@buckets, [ reverse splice(@from, 0, @from / $howmany--) ])
+ while $howmany;
   @buckets;
}
[download]

Or, dropping @buckets at the expense of readability (and perhaps efficiency):

sub split_into {
   my $howmany = shift;
   my @from = reverse @_;

   reverse 
      map 
      { [ reverse splice(@from, 0, @from / $_) ] } 
      reverse 1 .. $howmany;
}
[download]