Omega is a program built by extension of the TeX sources which works internally with 'wide' characters (it is capable of dealing with all of Unicode version 3); this allows it to work with most scripts in the world with few difficulties from coding schemes. Omega also has a powerful concept of input and output filters to allow the user to work with existing transliteration schemes, etc.
A part of the project is to develop a version of LaTeX to work with Omega, styled "Lambda".
Omega was first released in November 1996 by the project originators, John Plaice and Yannis Haralambous; a recent version is maintained on CTAN. General project information, as well as copies papers, are available via the project's web site.
Implementations of Omega are available as part of the teTeX, mikTeX, fpTeX and CMacTeX distributions (see TeX systems), as well as in TeX Live.
A related project, Aleph, has merged a version of Omega with the facilities of e-TeX, as a pathfinder for potential future Omega development.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=omega