Currently there is no commercial/pro version available (not sure about similar one's, there are some plugins that have small bits and pieces of the core edit flow functionality (Editorial Calendar comes to mind) but I'm not sure about one that unites all the functionality under one roof.
The plugin's taken a bit of a dive but we're working right now to get it back shape. Currently working on fixing up any hiccups with 3.6 and will continue to roll out new features once a firmer timeline is established.
Stay tuned, and if you're interested in contributing you'll definitely want to check out the GitHub repository: https://github.com/Automattic/Edit-Flow. Code contributions are by no means the only thing there's a need for. Reporting bugs and testing are vital pieces of the puzzle as well.
If you have anymore questions I'll be happy to answer them.