Synthesized singers

Freaky, now you can create synthesized singers from correctly annotated lyrics and scores — Slashdot | Yamaha Releases Singing Synthesis Software. I wonder what range of vocal performances this can encapsulate — I was listening to Led Zep/Robert Plant in the car this am, can you specify a vocal performance in his style? I am sure the answer is no, but how many iterations of Moore’s Law and algorithm development will we need before you can do something like this?