I do use:
subClass.prototype.constructor = subClass;
in the code. That is just for completeness as the prototype.constructor property by default points to the class constructor and we just want to maintain that since we blow it away with the line:
subClass.prototype = new inheritance();

The other reason I don’t like the JSON syntax is the increased likelihood of the old dangling comma that messes up IE – but to each their own

http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Reserved_Words

They are both just properties, but not part of the language, like “while”.

And here you use the constructor property too:
subClass.prototype.constructor = subClass;

Sure, the ClassName.prototype.method thing makes sense, but the JSON syntax makes more sense, and is easier to write.

Yah I don’t really like the ClassName.prototype.method thing either but for a lot of Java type people it makes sense :S

Can you explain those lines though:

// enable multiple inheritance
if (baseClass.base)
{
baseClass.prototype.base = baseClass.base;
}

Else i would rather write:
subClass.base.constructor = baseClass;

instead of
subClass.baseConstructor = baseClass;

because base is our pseudo keyword already, and constructor is one too…

What is still ugly for me, is that you have to write ClassName.prototype.method for each method you want to add.

A JSON syntax ala
ClassName.prototype =
{
method: function()
{
}
}

would be clearer. This could be easily achieved, if you write the prototype assignment in a for-in loop.

Could you please tell me more about your inheritance implemenation ??