  We present the experimental observation of the symmetric four-photon
entangled Dicke state with two excitations $|D_{4}^{(2)}>$. A simple
experimental set-up allowed quantum state tomography yielding a fidelity as
high as $0.844 \pm 0.008$. We study the entanglement persistency of the state
using novel witness operators and focus on the demonstration of a remarkable
property: depending on the orientation of a measurement on one photon, the
remaining three photons are projected into both inequivalent classes of genuine
tripartite entanglement, the GHZ and W class. Furthermore, we discuss possible
applications of $|D_{4}^{(2)}>$ in quantum communication.
