My cat has been in labor since last night at about 8:30 and she still hasn't had them how will I know if she is just about to have them

Here is some helpful information.
As interesting as birth is, you will need to leave her be while she is in labor.
Cats can actually postpone labor for for about 24 hours until she is comfortable again.

Giving Birth to Kittens (http://www.marvistavet.com/html/giving_birth_to_kittens.html)

Is she indoors where you can assure that she and the kittens are safe after she has them?