There's been a lot of confusion regarding Shaak Ti. Especially since the deleted scene from The Invisible Hand in the REVENGE OF THE SITH DVD shows Grievous killing her. Since that scene was cut it isn't considered to be part of the canon.
Then there's her possible death scene in the Jedi Temple. I've seen a still of that, with Anakin entering her chambers while she's seated, and he's preparing to kill her. That didn't make the DVD. But I think it might have made it into the novelization of REVENGE OF THE SITH, however I will have to check on that. But I know for certain that she was in the Jedi Temple at the time of Order 66 in the novelization.
Also, you can see Shaak Ti in the Council chambers in the movie. However, it's only as a hologram as Yoda meets with the High Council from Kashyyyk.