I've been focusing on interval training with a new program I started.
To bring out a six-pack you have to do 2 things - increase the muscle definition in you abs and lose fat all over. You can't really spot where the fat loss is focused, but you can spot which muscles to define.
I'd try working on losing a bit of fat by boosting metabolism and finding some excercies for defining the abs. If you do these two things, you should get results. I don't have much to lose - 10 lbs or so (not bad for a 35 year old) but even at my age I'm seeing more muscle definition.