mislav also has a git deployment project: https://github.com/mislav/git-deploy
If you read the website you will see that Git Pusshuten can do more than just do a simple "git push" like other solutions.
Git Deploy by Mislav makes the assumptions you work with: Passenger, Ruby on Rails, etc. Git Pusshuten doesn't make such assumptions. It allows you to deploy an application, regardless of whether you're deploying a Ruby, Python, PHP, etc application, to whatever web server by defining _your_ environment through modules.
Additionally, it allows you to provision and pre-configure your environment so you can be up and running with minimal effort and sysadmin knowledge. Other solutions will make you manually set up your environment by SSH'ing into the server to configure everything. Now, I am definitely not saying that that is a bad thing. I'm just saying that Git Pusshuten's _goal_ is entirely different from that of Git Deploy.
So what you're pointing out now would only work for people using Phusion Passenger and a Rack application. That's a limitation that Git Pusshuten is trying to avoid.
If you read the main page, you will (hopefully) in most cases come to understand what this tool does. You will remember it, then look at other projects that also handle deployment and see if they satisfy your needs. You make a list of the tools you might use and try them out. Now you're doing the comparison and "experiencing" what works best for you yourself, rather than listening to my (perhaps in 3 months) outdated information which might be inaccurate.
Now, for convenience I agree that I could make a list to summarize what this is all about but I'm not sure if there's any need for it. The 3 main aspects are covered: "Core", "Hooks", "Modules" and a video demonstrating something very basic.
Regardless, as I already said, any input is welcome and I'll certainly take it into consideration. Thanks!