So microwave is now on the app store. Though wave was just announced to be shut down, I had the app done already (though I was waiting for a wave server update so thread continuation and attachment uploading would work), and I just published it anyway. So here it is. Grab it while wave still works :). It supports offline, so you can cache some waves and read them on-the-go.
microwave on app store 23 August 2010