If $M$ is a <i>hyperfinite type $I\!I\!I_1$ factor</i>, then (at least conjecturally), its group of outer automorphisms is a $K(\mathbb Z,3)$.

This is based on the following three properties of that von Neumann algebra:<br>
&bull; The group of unitary central elements of $M$ is a circle, and thus a $K(\mathbb Z,1)$.<br>
&bull; The group of unitaries in $M$ is contractible.<br>
&bull; The automorphism group of $M$ is contractible (conjectural).

To see that $Out(M)\cong K(\mathbb Z,3)$, apply the long exact sequence of homotopy groups to the following two fiber sequences:
$$
U(Z(M)) \to U(M) \to Inn(M)
$$
$$
Inn(M) \to Aut(M) \to Out(M)
$$<hr>

As a consequence, we also get that $BOut(M)\cong K(\mathbb Z,4)$.

I recommend my talk "[A <i>K</i>(&#8484;,4) in nature][1]"  (MSRI, April 2014), for an explanation of how to realize $Out(M)$ as the automorphism group of a naturally occurring mathemtical object.

  [1]: http://www.msri.org/workshops/689/schedules/18246