The CPU is a MT6226 CPU http://www.infinity-box.com/wiki/index.php/Chinese_Miracle
As far as I can tell, the people who mod their i9s use SpiderMan for flashing firmware and MTK Flash Tools for reading firmware, all over a com port using a special cable.
Here's more info on what it runs and who makes it:
I initially bought one of these as a joke.
At first I hated it, but it really grew on me. Having an unlocked iPhone form-factor phone, that I can transfer anything I want to it, pictures, music, movies, all over usb, is really nice. I took it traveling and really liked having two batteries, especially after I started reading books on it. Say what you want about the new eBook readers, but I love having a backlit screen that can fit in my pocket, fit hundreds of books on microSD cards, and has a backup battery. I could read clearly at night in bed or waiting for the subway in poorly lit areas.
It's really funny to watch an iPhone user try to use my phone, because even though it looks nearly the same, the screen handles way differently, needing more of a tap than a slide.
I wouldn't buy one of these for running apps on, I would just use it for an eBook reader and phone. That's all I wanted out of it and it exceeded my initial expectations.
This is the one I have: http://product.madeinchina.com/CECT-i9-Quadband-Unlocked-Dual-Sim-PDA-Smart-phone/10618567.shtml
If all you want is a unlocked phone and eBook reader with awesome battery life, give it a try. But the article is right that it can't compare to an iPhone. The user interface sucks compared to Apple's product, especially when you move into the submenus.
When you don't know what to do, walk fast and look worried.