Here's mine:

#!/usr/local/bin/perl

@a=split(//,"1");  #easier to make test strings this way. :)
for (1..10) {
  print "@a\n";
  @b=();
  $a=join("",@a);
  while ( $a =~ /((.)\2*/cg ) {
    push (@b, (length $1, $2));
  }
  @a=@b
}
[download]

500 iterations of this took 1.15 seconds. 10 iterations running 1..35 took 18.73 seconds. For reference, I'm running this on an Ultrasparc-5.