This would have surprised many people, because historically Malays in Singapore have done badly in school (relative to the other racial groups). Initially I thought that Natasha's success might be a positive sign of a trend that the Malays are finally catching up.
However, the statistics don't bear this out. This MOE chart breaks down PSLE pass rates by race, over a 10-year period. We see that as a group, Malays still lag behind, and the gap isn't closing. So Natasha is an exception to the rule, rather than an indicator of a trend.
The blogger over here (Both Sides of the Johor Straits) notes, however, that in recent years, the minority races (Malays and Indians) seem to be statistically overrepresented among the very top PSLE performers. For example, the top PSLE student in 2005 was Malay. The top performer in 2006 was Indian. The top performer in 2007 was Malay.
This is interesting, because statistically, even if Malays, Indians and Chinese were academically equal (and they're not - as a group, the Chinese do better than the rest), the probability is that the top performer would be Chinese (as the Chinese are numerically, and by far, the biggest group).
So the blogger has a conspiracy theory. He thinks that the MOE is "cheating" to ensure that the top student is non-Chinese. MOE's rationale would be to raise the morale of the minority races and to provide a positive role model (bearing in mind that each year, the top PSLE student receives abundant publicity in the media):
All credits due to our top non-Chinese PSLE students, but I think that the recent trend in top non-Chinese PSLE students may indicate some backroom number-shuffling at MOE. Even though statistics & probability year-on-year predict that non-Chinese students do not fare as well at PSLE, I’ll not be surprised that the people at MOE have ways of ensuring a feel-good factor for all ethnic groups in Singapore (keeping in mind that PSLE exams scripts are marked in secret, the papers are not returned to students, the grades are not contestable and even the full-marks for each exam-topic are not revealed).
Assuming that the top students in 2007 scored full-marks for the Maths and Science papers (which is possible), Natasha must have scored nearly full-marks for English language and Malay language (full-marks in these papers are impossible), as she stood clear above her peers in terms of total marks for all papers. Having said that, a top Malay PSLE student as announced by MOE can do much to lift the spirits of the Malay community in terms of ethnic pride and reinforcing MOE’s ‘educational meritocracy’ policy.
Well, who knows. It's a possible theory, I suppose. However, I have a simpler alternative explanation.
In each year, all the PSLE students take exactly the same exams (English, Maths and Science) - except for the 2nd language paper. Here the Chinese take the Chinese Language paper; the Malays take the Malay Language paper; and the Indians take Tamil Language).
At the top end of the curve, the very best students are all striving to achieve marks as close to perfect as possible. For English, Maths, Science, they all take the same paper, so the same ultimate obstacles to a perfect or almost-perfect score apply to all.
However, if the Chinese Language paper is marked more rigorously than the other Language papers, then there would be a good probability that non-Chinese students would be statistically overrepresented at the very top end of the curve (where everyone is striving for perfect or almost-perfect marks).
It's not necessarily a deliberate attempt by the Education Ministry to engineer a non-Chinese top PSLE student. It may simply be that the Chinese Language exam is marked more rigorously, because that's the way the Chinese Language markers are. The glass ceiling would emerge in those sections of the paper which require the marker's subjective assessment.
For example, if there is an essay section worth 40 marks, and if in practice the Chinese marker is willing to give a maximum 35 marks for an absolutely brilliant Chinese essay, well, there's your glass ceiling.
On the other hand, If the Malay/Tamil marker has no qualms about giving 39 or 40 out of 40 marks for an absolutely brilliant Malay/Tamil essay, then simple probability tells us that there's a good chance that the overall top PSLE student could be non-Chinese.
This differential is too small to have any measurable effect of the respective PSLE performance of the racial groups, when we view them as a group. But this differential matters, when it comes to identifying the very best few students (eg the top 10) in the entire nation.
It's like Matt Biondi in the 1992 Olympics commenting that if he had grown his fingernails a little longer, he could have won the 100m men's butterfly gold medal. With short fingernails, he touched home one hundredth of a second slower than the winner, and had to settle for the silver medal.

By analogy, Singaporeans taking the PSLE Chinese paper could be swimming with short fingernails. Of course, for the vast majority of students, this is a non-issue. They don't swim fast enough for the length of their fingernails to matter.

That must be why I coudn't qualify for the Olympics."