Tim,
there's pop and then there's "pop"
Your image has the general seperation from the background that we see so often from shallow DOF but it's not the same as the pop marcus describes in Babi's shots for example.
Take a look at this one from babi
http://pics.meninenuotrauka.lt/e79/e79d0585723e9c9f78da31d8c9d56b15.jpg
Now that is pop. It's not just seperation from the background its a combination of
1.incredible depth because of the surroundings and the forgeound oof parts
2. contrast of the subject to the background
3. that rim lighting on the women in red's shoulders
4. the superb sharpening that really puts a crisp edge to the subject
5. bold colors
there's lots of examples throughout his site of this and you see the 5 things above popping up all the time. I really think the crisp edge has a lot to do with it down to a superb sharpening action.
I tried to find a good candidate in my own shots to see if I could replicate the effect with pp if some of the conditions above were present and found this one which only is missing the foreground interest. See the before and after, I tried to make the edges of the subject much crisper with a web sharpening action. What do you think, does it make a difference? By the way, I realise it's over sharpened - just trying to push it to see if that is a major factor
http://www.flickr.com/photos/37599844@N04/7655213428/
104 by
JoeBoyMan, on Flickr
http://www.flickr.com/photos/37599844@N04/7655213284/
104Pop by
JoeBoyMan, on Flickr