The plugin doesn't play nice with the new 3.3 beta release. There's a conflict with the tmce wysiwyg editor (jquery I guess). I get a second editor box on every page (bottom) and the tmce editor doesn't work anymore.
http://cl.ly/3O052T33392S3s3F1x0T
http://cl.ly/2n300N0C1D1325202k0v
http://wordpress.org/extend/plugins/developers-custom-fields/