Flutter has been a great plugin for WordPress, allowing CMS developers to leverage custom post types and write panels through an easy to use GUI. Unfortunately over the past year or so development has slowed down some, and has even forked into other projects.
According to many Flutter is still very much alive, but with the custom post types being built into 3.0 I think it’s apparent to Freshout, the company behind flutter, that 3.0 post types may eventually replace the demand for the plugin.
Magic Fields build on the core of Flutter, taking it furthur forward and squashing some tough to tackle bugs. If you dig Flutter, but can’t seem to come to grips with some of the bug fixes that are needed to make it run properly, I highly recommend checking out Magic Fields.