Further icy headers that winamp looks for, not sure about xmms. just replace your current headers with the below content.

        print $socket "ICY 200 OK\r\n";
        print $socket "Content-Type: audio/mpeg \r\n";
        print $socket "Cache-Control: no-cache \r\n";
        print $socket "Pragma: no-cache \r\n";
        print $socket "Connection: close \r\n";
        print $socket "icy-name: Fuelradio \r\n";
        print $socket "icy-genre: Techno \r\n";
        print $socket "icy-url: http://www.fuelradio.com \r\n";
        print $socket "icy-notice1:This stream requires Winamp \r\n";
        print $socket "icy-notice2:Perl Streamer v0.1a \r\n";
        print $socket "icy-metadata: 1 \r\n\r\n";
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additionaly you can add

print $socket "icy-metaint:8192\r\n";
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althoug my tests with the metaint caused alot of skipping and chirps, maybe someone can shed some light on the proper interval, im sure its different than 8192 since the mp3's are not being decoded and re-encoded within the scope of the app, there just being shoved down the throat. Anyone have ideas on how to do title streaming (i.e. showing what song is playing in the winamp/xmms title bar) maybe a id3 lib for perl??