overview
Io is a prototype-based programming language inspired by Smalltalk (all values are objects, all messages are dynamic), Self (prototype-based), NewtonScript (differential inheritance), Act1 (actors and futures for concurrency), LISP (code is a runtime inspectable/modifiable tree) and Lua (small, embeddable).
features
BSD license 
small vm (~10K semicolons) 
multi-state (multiple VMs in same process)
incremental collector, weak links
actor-based concurrency, coroutines
64bit clean C99 implementation
embeddable, exceptions, unicode
binaries
osx, 
windows,
freebsd, 
openbsd, 
netbsd
 
linux 
x86rpm,
x64rpm,
x86deb,
x64deb,
raspberry pi armhf 
binaries via 
jake peck