Google may give different results for their mobile browser and have longer term plans for SPFY type enhancements that take into account that you're using a mobi

Google may give different results for their mobile browser and have longer term plans for SPFY type enhancements that take into account that you're using a mobile device. I also think the mobile version would use fewer resources per search than the full featured, desktop search with Google Instant. Advertisers may also want to be able to target mobile users vs. desktop users separately.