So, there are a couple of problems with this study as presented. First of all, no one links back to the original study, which can be suspicious. Second, the idea that you can prove or disprove the existence of a piece of anatomy through the use of questionnaires is kind of funny. According to the articles I've read, the conclusions of the study hinge on the fact that they interviewed sets of identical twins: since some of the twins claimed to have g-spots and some didn't the researchers concluded the g-spot didn't exist. I don't think I need to point out the reasons why that's a bad conclusion (twins don't usually have the same sexual partners, don't have identical developmental experiences). They also claimed that since most of the women who claimed to have a g-spot were young, this also somehow proved its non-existence. Wha? The methodology here is seriously flawed.
One of the commentators on Jezebel pointed out that there's a huge variation in male genitalia. It would be ridiculous to assume that all penises had to be identical, so why do all vaginas have to be? As we in this community well know, anatomies vary widely, as does the kind of stimulation each person needs. The idea that "some women haven't found their g-spot, so all women must be making this up in their heads" is a pretty stupid thing to say.
The out-of-hand dismissal of women's sexual experiences is also kind of creepy. Here's a link to an interesting study which actually used imaging technology to observe the g-spot (a little more convincing than questionnaires): link