iCode is an "Integrated Development Environment" for creating Macintosh applications.
It is currently Alpha Quality so expect lots of rough edges.
The scripting language is JavaScript (using the SpiderMonkey engine from Mozilla).
The runtime environment is specific to iCode and presumes no knowledge of existing interfaces such as Carbon, Cocoa, etc, and is otherwise designed to be "more conventional".
For example, in Cocoa, one typical way to draw a line between two points would be expressed as:
[NSBezierPath strokeLineFromPoint:NSMakePoint(x1, y1) toPoint:NSMakePoint(x2, y2)]
whereas in iCode it would be:
Graphics.line(x1, y1, x2, y2)
This is by no means a condemnation of Cocoa - it's just that somebody new to programming on the Mac would find the latter a lot easier to pick up.