One of the main reasons for using RAW format is to preserve the original file in its untouched form, now with nondistructive editing i.e., Aperture, Nikon NX and Lightroom, is it still really needed?
Not exactly. Shooting in RAW is like shooting with film and getting a negative that you can do many, many things with to produce the print you want. Shooting in JPG is like using a Polaroid camera and ending up with a print at the end of the process, with which you can do very little. That's a pretty extreme example, but it's intended to show that you're capable of much more manipulation with a RAW file than you are with a JPG. Someone smarter than me will jump in soon and explain the technicalities better than I can.
Non-destructive editing is a different thing altogether. All it means is that you never alter the original image file as you edit it, regardless of whether it's RAW, TIFF or JPG. I use Aperture, in which you work with a Version of the original file rather than the original. All the version actually consists of is a collection of the commands that got you from the original image to the edited/tweaked image that you want to print or save and present to the world some other way, like the web. There are two advantages to this. First is that you haven't altered the original file. The second is that the Version takes up much less space on your hard disk than a second, altered copy of the original file does.
If you want to be able to edit your images and "enhance" them, then RAW still gives you much more information to work with than a JPG or TIFF will...and doing that enhancing with a non-destructive editor insures you'll always have your original, unaltered image file.
Hope that helps,