According to http://hyperpolyglot.org/lisp, the only falsehoods in Clojure are false and nil. Indeed, surprisingly enough, (Boolean. false)>
I think the reason this happens is that Clojure's = uses Java's equals method. So (= x y) is like x.equals(y). So false gets coerced into (Boolean. false) in the comparison under the hood.
Note that this does not mean that (Boolean. false) is false or that it is the 'same' as false, just that when false and (Boolean. false) are compared using the equals method they are considered to be equal.