[samth]

First, the Racket VM has been under development since 1995, so it's not "another VM".

Second, the Racket VM supports lots of things that other VMs don't: the Racket module system [1], kill-safe synchronization [2], custodians and eventspaces [3], first-class continuations, and many other things besides.

[1] Composable and Compilable Modules, Flatt 2002

[2] Kill-Safe Synchronization Abstractions, Flatt + Findler 2004

[3] Programming Languages as Operating Systems, Flatt et al, 1999