TalkPHP - Selecting Latest Forum Post Threads

I've made a simple user forum on a site. More along the lines of "threaded comments".

On my front page I'd like to show the top 5 latest commented threads.

IE - 5 Threads that received the latest comments.

Code:

CREATE TABLE `forumPost` (

  `id` int(5) NOT NULL auto_increment,

  `thread` int(5) NOT NULL default '0',

  `text` text NOT NULL,

  `user` int(5) NOT NULL default '0',

  `date` datetime NOT NULL default '0000-00-00 00:00:00',

  PRIMARY KEY  (`id`)

) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=7 ;

Code:

CREATE TABLE `forumThread` (

  `id` int(11) NOT NULL auto_increment,

  `title` varchar(255) NOT NULL default '',

  PRIMARY KEY  (`id`)

) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;

I'm having trouble with the query logic.

Basically something like:

Code:

SELECT * FROM forumPost GROUP BY(DISTINCT(thread)) ORDER BY date DESC

obviously this doesn't work. Any ideas on how to do this without going the easy PHP route?

Thanks
jw