I have seen this, as soon as those spam updates started from Google, a site of one of my friend was blasted massively, don't know who, but maybe one of the competitor I guess and the site was in 2nd page soon after. The surprising thing was, in a week the site was on 1st place, which was on 4th before blasting. After that, I thing not everything works as NSEO. Yes, I'm afraid to do that myself.
On the other hand, we discussed and tested on a new site and it was soon on 1st page, but not on 1st place though and then it vanished. So, I'm still confused if NSEO exists or not.