"Study Links Perfect Pitch to Tonal Language"
   from The New York Times

Most native speakers of languages that use tones to convey meaning may
have a form of perfect pitch, according to new research.  The results
may suggest that many or even most babies are born with perfect pitch
but lose it if they do not learn a tonal language or undergo early
musical training.

Most people find it easy to perceive and sing musical tones relative
to each other, a skill called relative pitch, but perfect pitch -- the
ability to identify any note by name or to sing a given note without
hearing a reference note beforehand -- is much less common.  Perfect
pitch turns up in no more than one person out of 10,000 in Western
countries, according to some estimates.

http://www.nytimes.com/library/national/science/110599sci-language-pitch.html