In what probably shouldn't come as a surprise to anyone, Microsoft has confirmed that yes, the Xbox 360's successor is already being worked on. According to Microsoft EMEA (European, Middle East, and Africa) vice president Chris Lewis:
"The consumer won't let you [rest on your laurels], the developers certainly won't let us. So that's happening right now. You'll see more [on a new Xbox] over time...certainly we're not talking about the next version yet. So give us a chance to catch a breath, will you?"
Guys, please take your time; we haven't yet finished this round of "console X is better than console Y," and I think I need at least three years before I'm prepared to go through the "next-generation console holy wars" again.