The guy who wrote the more "composed" pieces of the soundtrack for the FMVs is Josh Gabriel, most famous for being half of the electronica duo Gabriel & Dresden. He nows tours solo, but is also a big name in the sound engineering world. See
Wikipedia for more details, but as far as I'm aware he's not worked on any other games. He worked at Oddworld because he's a college friend of Lorne's.
The more minimal and atmospheric gameplay music is done by Ellen Meijers (credited as Ellen Meijers-Gabriel in AE. She's worked on more games, according to
Wikipedia and
her website.