Can Chris stop someone from using his name and likeness without his consent? Possibly, under right of publicity laws, but the ones I'm most familiar with preclude unauthorized commercial uses, and the jurisdictional variations are a nightmare.
Can't Chris sue for defamation if someone is falsifying things he supposedly said and did? Perhaps, but parody is a First Amendment defense to defamation.
Is this parody? No one here has identified themselves as the "fake" Chris Pirillo. Under trademark law apparently, "A parody must convey two simultaneous--and contradictory messages; that it is the original, but also that it is not the original and is instead a parody. To the extent that it does only the former but not the latter, it is not only a poor parody but also vulnerable under trademark law, since the consumer will be confused." From Cliffs Notes, Inc. v. Bantam Doubleday Dell Publishing Group, 886 F. 2d 490 (2d Cir. 1989). (Via Chilling Effects) (I'm not sure if the same requirement extends to parody in general, and haven't quickly found anything on point.)
Does Chris have trademark rights in "Chris Pirillo?" Let's assume yes. And let's assume he wanted to put a stop to someone else's use of pownce.com/chrispirillo. Do anti-cybersquatting laws extend to other level domains? Is something to the right of .com, etc. even an other level domain? Would Chris have recourse against Pownce, the faux Chris Pirillo Pownce user, or both?
(My head hurts.)