gistfile1.js

// This is in the controller
 formatExposureTitle: function () {
        SC.RunLoop.begin();
        var value = ExposureViewer.getPath('exposureNumber.value');
        console.log(value);
        console.log('formattedExposure!');
        this.set('formattedExposure','Exposure #' + value);
        SC.RunLoop.end();
    }.observes('ExposureViewer.exposureNumber','ExposureViewer.exposureNumber.value')
});

// This is in the view
 exposureLabel: SC.LabelView.design({
                    layout: {
                        top: 5,
                        left: 20,
                        width: 60,
                        height:20
                    },
                    classNames: ['label-black'],
                    valueBinding: 'ExposureViewer.exposureController.formattedExposure'   
                }),