Unladen Swallow 2009Q2 released

The useful thing isn't the type checking but rather the fact that variables have to be declared in a lexically enclosing scope, which means that trivial typos are compile-time errors rather than runtime errors (when that line is actually reached). Also important are things like calling functions with the wrong number of arguments (swapping % and , in function calls). And it's hard to write unit tests for cases which shouldn't be reachable, but which are important for reporting when unexpected things happen.