One member pointed us to this archived news from the Star newspaper from this article dated Aug 2, 2009 titled "Pupils To Sit For Aptitude Test On The Last Day Of UPSR". This was to have taken effect in 2009 so it is certainly not a new thing at all. According to the article "The Aptitude Test grade will be listed in the UPSR slip but will not count towards the final result." It also mentioned that "pupils in national schools would sit for the test in Bahasa Malaysia while those in vernacular schools would have theirs in Chinese and Tamil respectively."
The 1 11/2 hour paper consists of 60 objective questions and will test students in the area of thinking skills, problem solving and decision making and interests. It has some IQ style tests as well as asks students to list out their areas of interests and what motivates them.
If you are interested to find out more about this paper, you can visit this teacher's blog. He has uploaded some sample papers for the Ujian Aptitud UPSR Tahun 6.
This link leads you to the UPSR 2014 examination timetable. If your child is sitting for the UPSR in subsequent years, you can still view the timetable to have an idea of the schedule.