If the thing is meant to live on your coffee table and couch, then a couple of hours is good enough. Just design an attractive charging station/stand so it can charge while it goes into "picture frame mode."
Another stand so that it can be used as some kind of secondary display would be cool. (Maybe not a real display, but one driven by something like VNC?)
If it runs Linux, Mac OS X, or Windows, just use synergy. It lets you share keyboard and mouse between several systems. It's awesome. The kind of OSS software I'd love to pay for.
Another stand so that it can be used as some kind of secondary display would be cool. (Maybe not a real display, but one driven by something like VNC?)