I did some googling out of curiosity and was actually kind of surprised to find out that, statistically, synesthesia affects about 3-5% of the population. Certainly uncommon, but not as rare as I expected.

http://sro.sussex.ac.uk/14073/1/p5469.pdf

http://www.daysyn.com/Types-of-Syn.html

Unfortunately, couldn't find that much data on the specific kind of "time-space" synesthesia that was mentioned in the article. Bummer.