I'd love to do a sequel. It will probably be a while, though, for several reasons: a) Right now, I'm too busy playing Portal 2; b) I'd want to take some time figuring out how to change some things up a bit, as part of the concept was that players were operating somewhat in the dark; and c) I'm actually brewing a different game idea that I think you guys will love. If I can get the details worked out, I'll start that when my Portal 2 fixation dies down. If not, or after that other game, I'll give some consideration to Oni II.
That being said, if someone else wants to host an Oni-style game, my feelings wouldn't be hurt in the slightest. It'd be fun to experience it from the other side. But either way is fine with me.