Who says you only have one radio? Why not take an Airport-equipped PowerBook and add in a Lucent PC Card? There'd still be some software manipulation to do (to include power management; can't imagine the draw with two 802.11b transceivers running simultaneously) however, much of it could tap into the advanced networking in 10.2.

For that matter, USB 802.11b might be a possibility for iBooks, though I'm reluctant to recommend USB as a connection for networking!