Jsut thought id psot up these vids of this so you can all becmoe little hackers, but seriously dont do this.
http://uk.youtube.com/watch?v=-8hZT181Bj8
http://uk.youtube.com/watch?v=nYYiKay5AsA&feature=related

One of the comments:

"Good news valve has answered me for reporting this thru game, and that they are aware of it and will fix it in the coming weeks.

But they said they would prefer that you remove this video, as to prevent more people from exploiting it. I'm happy it helped, but I dont want to see more cheaters, so I too think it's better to remove it."

It has been posted a fair bit on the official forums too, so it wouldn't surprise me if it was patched out soon.

Im only posting it as i find it quite amusing a heavy jumping like a scout It like defys the laws of gravity. Besides i know that the people round here wont do this stuff.

Speaking of which I posted why the Scout is the best class on the steam forums, I think I'll make a new thread here to enlighted everyone

I think the second link is better, as it demonstrates why you shouldn't use this exploit.

Yeah I know, I didn't even think that was possible

Imagine putting a sentry on the spot the guy in the second vid reaches
I think the music in the first one sucked compared to the second, but yeah...

I dont think this exploit is of much use, why should i want to jump on the health at spawn or jump as a heavy over the little wall on the last cap in granary? Better go round the corner and start shooting straight away! (yeah, I know -> )

Valve will fix it soon enough

Do You?