How random do you want it, and what do you mean by "randomize"? I assume you want a random permutation, all permutations equally likey.

The traditional solution is something like:

for $i ($#array..0) {
  my $j = rand($i);
  @array[$i,$j] = @array[$j,$i];
}
[download]

This does @array swaps, and can be shown (see Knuth) that all permutations are equally likely -- assuming I haven't made any coding mistakes

This is probably the fastest randomization algorithm, although various implementations might be faster than mine.