while (<DATA>) {
    @res = /(\d{4}(?:-\d\d){2}).*dates processed: (.*)/;
    warn "@res";
}

__DATA__
2009-02-02 06:12:57,500 dates processed: 2009-01-31, 2009-01-29, 2009-01-30
2009-02-18 06:03:47,713 dates processed: 2009-02-16, 2009-02-17
2009-02-19 05:58:29,138 dates processed: 2009-02-18

##</code><code>##

2009-02-02 2009-01-31, 2009-01-29, 2009-01-30 at tst.pl line 3, <DATA> line 1.
2009-02-18 2009-02-16, 2009-02-17 at tst.pl line 3, <DATA> line 2.
2009-02-19 2009-02-18 at tst.pl line 3, <DATA> line 3.

##</code><code>##

use Data::Dumper;
while (<DATA>) {
    @res = map { split } /(\d{4}(?:-\d\d){2}).*dates processed: (.*)/;
    warn Dumper \@res;
}

__DATA__
2009-02-02 06:12:57,500 dates processed: 2009-01-31, 2009-01-29, 2009-01-30
2009-02-18 06:03:47,713 dates processed: 2009-02-16, 2009-02-17
2009-02-19 05:58:29,138 dates processed: 2009-02-18

##</code><code>##

$VAR1 = [
          '2009-02-02',
          '2009-01-31,',
          '2009-01-29,',
          '2009-01-30'
        ];
$VAR1 = [
          '2009-02-18',
          '2009-02-16,',
          '2009-02-17'
        ];
$VAR1 = [
          '2009-02-19',
          '2009-02-18'
        ];