Comment by chops

Erlang version for you:

  -module(sleepsort).
  -export([sort/2, spawn_waiters/3, wait/4]).

  sort(Xs, Conv) ->
   spawn(?MODULE, spawn_waiters, [Xs, Conv, self()]),
    receive
        {spawned, N} -> queue(N)
    end.

  queue(N) -> queue(N, []).
  queue(0, Xs) ->
    lists:reverse(Xs);
  queue(N, Xs) ->
    receive
        {item, X} ->
            queue(N - 1, [X|Xs])
    end.

  spawn_waiters(Xs, Conv, P) -> spawn_waiters(P, Conv, Xs, 0).
  spawn_waiters(P, _, [], N) ->
    P ! {spawned, N};
  spawn_waiters(P, Conv, [X|Xs], N) ->
    spawn(?MODULE, wait, [X, Conv(X), P, self()]),
    receive
        monitored -> ok
    end,
    spawn_waiters(P, Conv, Xs, N + 1).

  wait(X, T, Q, P) ->
    Ref = erlang:monitor(process, P),
    P ! monitored,
    receive
        {'DOWN', Ref, process, P, _} -> ok
    end,
    timer:sleep(T),
    Q ! {item, X}.

Edit: finally got the formatting right.