I suspect the JP version of yahoo is doing its own thing now, what with Western yahoo using bing results. All a bit suspicious, though. :(
Also been seeing a (typical) SE kludge of yahoomobile coming in as a bot and as a proxy. I blocked first as one, now as the other. I do wish these companies would sort out their IP ranges properly. Still, a dual IP usage by yahoo isn't as bad as google's 6 or eight, I suppose. :(
Apart from the underline strange bot UA and the now-fixed 157 IP bot-range, MS seem to be quite reasonable and consistent on IPs. Which makes a nice change.