Well the best lip sync method I've come across is in a book called stop staring by jason Osipa. (worth grabbing if you are interested in facial animation but it is written with Maya terminology.

Essentially the basic setup goes like this.

1. create a neutral expressionless face as the default.
2. create an open shape. just the lower jaw moving down.
3. from the neutral shape create a narrow shape, like a closed "ooo" sound.
4. create a wide shape.
5. add a morpher modifier to the neutral mesh and add each of the 3 shapes. then you can animate them mixing together
to create all the different shapes you want. eg. open and narrow= "OH" open and wide="Ahh" a tiny bit of open and wide= "Eee" etc..
Theres alot of good tips in the book and he goes way further with his rigs and his animation tips about performance and sync etc..
hope that helps.

and heres a link to some of the book. worth a read.

[Link to books.google.com.au]

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