Z-Wave lighting question

Yes it can.

But do you already have a 3 way switch setup?

You can do it cheaper then with the AS101 & a 3 way switch.

Instant status you better wait for the Pro line from Intermatic or Leviton. ACT works by polling.
My hall light is set-up as a 3-way (controlled by two switches). I want to use the ZDW120W because it has instant status capabilities when hooked up to Homeseer.