Surely this is an announcement in itself. They are confirming that they're working on it and it will appear at some point. Personally, unless it streams games, I'd consider it a pointless PC. The graphics card wont be good enough. Although I do hope it has the orange value stuck to the top.
No if they have any sense they will wait till after Sony & Microsoft push their consoles out the door. Then launch a underpowered Steambox with a modular Motherboard. The games will look just the same as "next gen" consoles, then 2-3 years later the Steambox will start to offer upgrades. That will put their hardware ahead by a large margin.