I've played with 'serrating' my edges a variety of ways in the past. It was a real pain to do and I didn't make the effort to do it particularly well.
After regular sharpening I used a few *very* firm strokes of course sand paper run downward against the side bevel using a block of wood. This took little nicks out of the edge and left gouges along the side of the metal. I also tried using a triangular file to increase the depth a little but wanted it reversible so didn't go very deep.
I did the first 6 inches at the tip and tried that, then did longer stretches from the tip to (eventually) all the way past the sweet-spot and even back past the section under the boot.
If done only at the tip the ski seemed to work best overall in many conditions with the tip being perhaps overly responsive to gripping and provided for sharper turn entries on very firm and icy slopes. Doing it past the mid section really helped on ice in that it seemed to dig in and hold much better though it also slowed me down (perceptibly) from what I'd have otherwise expected, making steep ice a lot easier to ski slower on. Not exactly what you'd want for racing...
Serration made no worthwhile difference on soft snow and it probably just slowed me down a tiny bit more (unnoticeable).
I think the reason that serration never took off (in this form) is that it doesn't provide anything really useful that can't be had by other, less destructive means. It would be very hard to keep up (special equipment required) and would easily be damaged by a rock (instead of a rock putting in a new 'serration', sliding along a rock would wreck or wipe out existing serrations!).
In the end, it made for an interesting experiment but took a lot of work to put in and far more edge-work to repair the edges afterward.
The other form of "serration" (not really) is currently being produced on both skis and boards in the form of a 'wavy edge' pattern where the edge is mounted in a series of undulations out from the side of the board (see the link posted by Wibby above). I've a friend who's been on the snowboard version and really likes it - especially in icy conditions. And this version of 'serration' is easily maintainable.