We've a Windows VM thanks to Andy.
There's an Linux VM and a pre-built Exupery development image. There's also entries in SqueakMap and Package Universes.
Links to the pre-build items are here: http://wiki.squeak.org/squeak/3945
The Package Universes Exupery Development package doesn't fully work. To use it load CommandShell from SqueakMap after loading it. This is because GraphViz needs the latest CommandShell which hasn't yet made it to universes. I've emailed Lex to get this sorted.
Bryce