The Roku products definitely had the "look" but they didn't have any software. Their products all suck to put it bluntly.
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For a long time it seemed like running SlimServer was the way to get decent streaming on your SoundBridge products.
I believe Soundbridge sales took a huge dive when Slim Devices introduced their newer lineup (SqueezeBox 3).
I'm not sure how everyone's market share is divided right now, but I believe Sonos is still dong quite well as they've always had a good balance of nice looking hardware and software.
Slim Devices is growing slowly but surely after its acquisition by Logitech.