I am considering these two pianos and I want to know if there was any upgrade from the Casio PX-130 to the PX-150?

Entirely different action. Most people seem to agree it is far better. (Improved piano sound, too.)

how does the action of the casio px-150 compare to the action of the yamaha p-155?

Adak,
Action on a piano is a subjective thing. You have to experience it yourself so that you formulate opinions on what you like and want. There is no wrong or right action. It's what feels right to you. The P-155 has an action that is considered by many to be very good to excellent. The action on the new Casio PX-X50 line has been improved over what the last generation had. Whether you like the action on either paino is a subjective thing that you need to decide for yourself.

I think the P155 feels more firm than the the PX150.

However I have little experience, and my impressions after spending a considerable time in a room full of several keyboards (Yamaha P105, P155, Casio PX150/350, Roland RD300NX, RD700NX, Korg 250) is that these keyboards are all more alike than they are different. Or perhaps that the differences are not so easily summarized by simplistic descriptions like "more firm". The only particularly strong impression I came away with was that the RD300NX keys didn't seem to return as well as any of the other keyboards, to the point where I wondered if this floor model had been particularly abused.

I've never touched a PX130, so I can't comment there.

tom

which action does the px-3s use? the px-130 or px-150?

Basically 130 with an ivory finish (though not the same ivory finish as the 150, more subtle).