It didn't work at first, made some changes in the code:
The variable gplayer at line 113 in file 'ssg_google_audio.php':
$gplayer = '<script type="text/javascript">
swfobject.registerObject("ssg_gplayer_object-'.$post->ID .'-'. $i.'", "9.0.0", "'.WP_PLUGIN_URL.'/ssg-wordpress-google-audio-player/swfobject/expressInstall.swf");
</script>
<div class="ssg-gplayer" style="width:'.$width.'px;">
<span class="title">'. $texts[$i].'</span>
<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="'.$width.'" height="'.$height.'" id="ssg_gplayer_object-'.$post->ID.'-'.$i.'">
<param name="movie" value="http://www.google.com/reader/ui/3523697345-audio-player.swf?audioUrl='.$hrefs[$i].$ap.'" />
<!--[if !IE]>-->
<object type="application/x-shockwave-flash" data="http://www.google.com/reader/ui/3523697345-audio-player.swf?audioUrl='.$hrefs[$i].$ap.'" width="'.$width.'" height="'.$height.'" id="ssg_gplayer_object-'.$post->ID.'-'.$i.'">
<!--<![endif]-->
<a href="http://www.adobe.com/go/getflashplayer">
<img src="http://www.adobe.com/images/shared/download_buttons/get_flash_player.gif" alt="Get Adobe Flash player" />
</a>
<!--[if !IE]>-->
</object>
<!--<![endif]-->
</object>
</div>';
Changed it to:
$gplayer = '<p class="mp3_post_'.$post->ID.'">'.$texts[$i].'</p><embed type="application/x-shockwave-flash" src="http://www.google.com/reader/ui/3523697345-audio-player.swf" flashvars="audioUrl='.$hrefs[$i].$ap.'" width="'.$width.'" height="'.$height.'" quality="best"></embed>';
Works for me, thought i could share it :)