This is why I don't even make lists. And when I did, what pissed me off was members that nagged me about updating it. With that said, please don't do it. Those are some of the biggest threads in the section, and they don't need members breathing down their necks about updating a list. It's not like it really matters if you're on a list. You're doing the challenge and updating in the thread. I'd say that's proof enough that you're participating.
Sorry, I just felt like I needed to say something on that subject, since I know I hate getting nagged about lists and other things. You know, we all do have things to do outside of PC and challenges.