TechDirt has an interesting look at some of the questions arising about the copyrightability of Twitter messages
. I haven't seen any actual copyright lawyers weigh in yet, but it certainly will be interesting to watch the feathers fly until someone nails down the answer. "[...] it seems like there would be two issues here. The first is whether or not the content is covered by copyright — and, for most messages the answer would probably be yes (there would need to be some sort of creative element to the messages to make that happen, so a simple 'hi' or 'thanks' or whatever might not cut it). But, the more important question then would be whether or not ESPN could quote the Twitter message. And, there, the answer is almost certainly, yes, they could, just as they could quote something you wrote in a blog post."