We prove a conjecture of Rognes by establishing a localization cofiber
sequence of spectra, K(Z) to K(ku) to K(KU) to Sigma K(Z), for the algebraic
K-theory of topological K-theory. We deduce the existence of this sequence as a
consequence of a devissage theorem identifying the K-theory of the Waldhausen
category of Postnikov towers of modules over a connective A-infinity ring
spectrum R with the Quillen K-theory of the abelian category of finitely
generated pi_0(R)-modules.Comment: Updated final version. Small change in definition of S' construction
and correction to the proof of 2.