Strange that you're focusing on the "Steam Box" entry when we already know that the internal name for their hardware project is "BigFoot" and there's a mailing list for "BigFootDev".
Forget Half-Life, there's not going to be a new one any time soon. I think Marc Laidlaw's recent comments show that although he would like there to be another game he doesn't have enough support from the rest of the company to actually make it happen.
While making cryptic comments about secret Valve news is an incredibly cheap (and easy) way to generate page hits, people really should have learned by now that it's never going to be anything to do with a new installment of a Valve game unless Valve themselves say it.
And as for Half-Life...
Anyone expecting anything vaguely Half-Life-related is going to be disappointed. As always.
Some sort of demonstration of a new controller seems plausible.
Gamestop has been doing this for ages. They make up an end-of-quarter release date to convince people to pre-order and just change it when that date passes. Last year it was 31/12/2012, now it's 30/06/2013.
In 3 months' time they'll change it to 31/12/2013.