I'm working on another plugin for Movable Type, and I wrote some decent Perl code for parsing RSS 2.0 documents. Here it is, so anyone can use it if they need to do something similar.

This converts a date taken from a RSS feed and converts it into a format suitable for database storage:

sub buildSqlDate
{
    my $str = shift;
    my @pieces = split(/ /, $str);    
    my $retVal;

    my $day = $pieces[1];
    my $month;
    if ($pieces[2] eq "Jan") { $month = 1; }
    elsif ($pieces[2] eq "Feb") { $month = 2; }
    elsif ($pieces[2] eq "Mar") { $month = 3; }
    elsif ($pieces[2] eq "Apr") { $month = 4; }
    elsif ($pieces[2] eq "May") { $month = 5; }
    elsif ($pieces[2] eq "Jun") { $month = 6; }
    elsif ($pieces[2] eq "Jul") { $month = 7; }
    elsif ($pieces[2] eq "Aug") { $month = 8; }
    elsif ($pieces[2] eq "Sept") { $month = 9; }
    elsif ($pieces[2] eq "Oct") { $month = 10; }
    elsif ($pieces[2] eq "Nov") { $month = 11; }
    elsif ($pieces[2] eq "Dec") { $month = 12; }
    my $year = $pieces[3];

    my $time = split(/\:/, $pieces[4]);
    my $hour = $time[0];
    my $min = $time[1];
    my $sec = $time[2];

    my $ts = $pieces[5];

    $retVal = "$year-$month-$day $hour:$min:$sec";

    return $retVal;
}

This will process a RSS 2.0 document:

sub processRSS20
{
    my $doc = shift;
    my $channelNumber = shift;

    my @channels = $doc->getElementsByTagName("channel");

    unless (length(@channels) >= 1) { die("No channels found in the feed, stopping"); }
   
    my $channel = $channels[$channelNumber];
    my $copyright = $channel->getElementsByTagName("copyright")->[0]->getFirstChild()->getData();
    my $description = $channel->getElementsByTagName("description")->[0]->getFirstChild()->getData();
    my $docs = $channel->getElementsByTagName("docs")->[0]->getFirstChild()->getData();
    my @entries;
    my @entriesTags = $channel->getElementsByTagName("item");
    my $generator = $channel->getElementsByTagName("generator")->[0]->getFirstChild()->getData();
    my $language = $channel->getElementsByTagName("language")->[0]->getFirstChild()->getData();
    my $lastBuildDate = $channel->getElementsByTagName("lastBuildDate")->[0]->getFirstChild()->getData();
    my $link = $channel->getElementsByTagName("link")->[0]->getFirstChild()->getData();
    my $title = $channel->getElementsByTagName("title")->[0]->getFirstChild()->getData();
    my $etr = @entriesTags;   

    foreach my $entry (@entriesTags)
    {
        my %data = {};
        my @catArray;

        $data{title} = $entry->getElementsByTagName("title")->[0]->getFirstChild()->getData();
        $data{description} = $entry->getElementsByTagName("description")->[0]->getFirstChild()->getData();
        $data{"link"} = $entry->getElementsByTagName("link")->[0]->getFirstChild()->getData();
        $data{guid} = $entry->getElementsByTagName("guid")->[0]->getFirstChild()->getData();
        $data{pubDate} = $entry->getElementsByTagName("pubDate")->[0]->getFirstChild()->getData();

        my @categories = $entry->getElementsByTagName("category");
        foreach my $category (@categories)
        {
            push(@catArray, $category);
        }
        $data{categories} = \@catArray;

        my $etr = @entries;

    }

    my %retVal;

    $retVal{copyright} = $copyright;
    $retVal{description} = $description;
    $retVal{docs} = $docs;
    $retVal{entries} = \@entries;
    $retVal{generator} = $generator;
    $retVal{language} = $language;
    $retVal{lastBuildDate} = $lastBuildDate;
    $retVal{"link"} = $link;
    $retVal{"title"} = $title;

    return \%retVal;
}

I've tested it locally on a copy of my blog's RSS feed. It should work fine for everyone else for basic parsing.