the new york times has an interesting article about new "voice fonts":
These fonts are made up of a database of phonemes, the basic sounds that make up any language. To create the database, technicians record a singer performing as many as 60 pages of scripted articulations (like "epp, pep, lep"). Assorted pitches and techniques like glissandos and legatos are also thrown in the mix; with all the combinations, the process takes a week of five-hour singing days.
i'd really love to hook this, or something like it, up to my computer-generated poetry page (which also uses a database of phonemes) to produce computer-generated music. it doesn't look likely i'll be able to do something like this any time soon, but maybe some day.