as far as i know there was a commercial solution advertised sometime ago. not sure about its UNICODE conformity.
ICTA has just put out a call for this (among other things). my mac still is unable to render sinhala properly though bala says he sees it perfectly with the same font (bhashitha). idea in ICTA call is to develop input method for mac together with getting UNICODE fonts to work.
University of Colombo School of Computing
Phone: +94112158953; Fax: +94112587239
From: "Harshula" <firstname.lastname@example.org>
Cc: "Ruvan Weerasinghe" <email@example.com>
Sent: Tuesday, February 1, 2011 10:07:19 AM
Subject: Is there a Sinhala font that ships with Mac OS X?
Vinton G. Cerf noted in his keynote speech at linux.conf.au 2011 that
Apple should be blamed for his slides containing outlines of squares
instead of Sinhala script for localised domain names. :-)
See at 11 mins 30 seconds of his talk:
Does anyone know if there are any plans for Mac OS X to ship a Sinhala
font? I recall Nick made one for Mac OS X
(http://web.nickshanks.com/fonts/sinhala/). Is anyone in touch with the
Apple folks? GNU/Linux and MS Windows already ship with Sinhala fonts.