Sony's new AirPlay-ready, lampshade-looking SA-NS 500 portable speaker looks like it's going to be pretty good. The SA-NS 500 has a four speaker array, a mid-range subwoofer, and gets 5-6 hours of battery life.
It also supports party streaming, which lets you play the same audio on multiple devices across multiple rooms—similar to a Sonos system—and can be controlled by Android and iPhone apps (no WP7 for now). It'll be available for $400—the same price as the Sonos Play:5—in October. [ThisIsMyNext]