Cartoonish looking images... lowered detail

Can somone help me out and tell me what filters etc they have used to create this cartoonish looking 2d people from a normal image...

http://www.glinedesign.com/blockpar...p_outlawz-a.jpg

Reverse-engineering? Crazy! I'd have to see the picture it came from to be sure but I'd guess that the palette was altered to use fewer colours. Could be by taking an indexed colour file from a palette of 256 colours to somewhere around 8 or 16. You'd lose a fair amount of colour in their skin tones that way though, so you would probably need to do a colour balance, replace colour or brightness/contrast adjustment afterwards.
If you are going for a cartoony look you could also try a serious "unsharp mask..." filter on it. Set the amount right up to like 500% (or more) and then play with the radius (depends on detail/size of image you're messing with).
Good luck!
P.S.: Sorry about the spelling, but that how we spell "colour" here, eh?