a famous problem of murray and von neumann (1943) asks whether the ii$_1$ factors $l(\bbb f_n)$ associated with free groups with $n$ generators, $\bbb f_n$, are non-isomorphic for distinct $n$'s. while this problem is still open, its ``group measure space'' version, showing that the ii$_1$ factors $l^\infty(x)\rtimes \bbb f_n$ arising from free ergodic probability measure preserving actions $\bbb f_n\curvearrowright x$ are non-isomoprphic for $n= 2, 3, ...$, independently of the actions, has been recently settled by stefaan vaes and myself. i will comment on this, as well as on related results by gaboriau, ozawa, ioana, peterson.