Actually, I was using CPActiveRecord for some time on my application before writing CR (I even contributed a couple of small things to his library). However, my application's needs outgrew that library and as I spoke with Nick he stated that it might take a rewrite on his part to facilitate them. That is when I decided to write a separate library.

There may be one or two lines of code borrowed, but more importantly I borrowed a lot of the good ideas Nick included (specifically, the notification system). I also borrowed ideas from ObjectiveResource as that project has a very similar goal.