Try this for starters (not meant to be a comprehensive rewrite):

#!/usr/bin/perl -w
open PASSWD, '/etc/passwd';
my @newarray;
while (<PASSWD>){
  my ($user,undef,$uid) = split(/:/);

  push (@newarray,$user) if $uid > 1000;
}

foreach $i (@newarray) {
 system ("find '/home/u1' -user $i -print > $i");
}
[download]

Thanks to vynce for pointing out the undef. Also to jeffa for:

my ($user,$uid) = (split(/:/))[0,2];
[download]