There are a variety of rendering technologies that have some support for Myanmar Unicode. The main ones are:
Myanmar Unicode requires a set of font specific rules to control the contextual substitution and reordering needed for correct rendering. OpenType and SILGraphite store the rules as extra tables inside the TrueType font itself.
The MyMyanmar project is interesting because it is attempting to include OpenType, Graphite and ATT tables into one font to produce a truly platform independent rendering solution for Myanmar.
The XenoType Burmese Language Kit provides a commercial Unicode 5.1 compliant font for the Mac.
M17N (Linux, LGPL) has support for one Myanmar font, but the Myanmar support may not be maintained. M17N stores the rendering rules in a separate file that must be installed at the same time as the font.