I'm sure someone in the know told me his real name a couple years back (he wrote the foreword to my book) and it certainly wasn't Jonathan Gillette. Of course, he might have changed him name again.. :)
To update, I've received a few anonymous e-mails with significant proof that the Jonathan Gillette theory is sound (though I won't go far as to say it's 100% certain).
This might also be the reason that _why just upped an ran. Staying anonymous is one thing, but letting someone else take the hit for you is quite another.
disclaimer: I don't know how long the blog has been trying to figure out who _why is.