Taku is just a codename for the minimum list of components you need to have Qt 5 running on the hardware. Nothing else, really. This project puts all the focus on Qt 5 and, of course, the Raspberry Pi. There is no willingness to join the OS discussions at all.
In fact I carefully avoided the word "OS" in the wiki page, referring to 'Linux stack' or 'dependencies' precisely to stay away from this expectation. Surely I could have done better since the first thing vgrade tweeted (actually the second) was about "#nokia #taku" which is just plain wrong. Taku doesn't aim to become an OS, it is definitely not something that is developed by Nokia. There is a couple of engineers that happen to work at Nokia, a couple of enginners that happen to work at ICS and that is pretty much about it. Qt 5 and Raspberry Pi is what matters here.