It looks like we will finally be getting some more details about the Steambox early next week, as Valve have posted a teaser webpage on Steam.
It’s suitably cryptic, but certainly hints at big things ahead, with the page stating that, “Last year, we shipped a software feature called Big Picture, a user-interface tailored for televisions and gamepads. This year we’ve been working on even more ways to connect the dots for customers who want Steam in the living-room. Soon, we’ll be adding you to our design process, so that you can help us shape the future of Steam.”
There are a trio of circles with faint symbols inside which look like so:

The first of these circles has a countdown timer which is set to run out at 6PM BST on Monday 23rd of September, next week. At that point, we’ll either get more tangible details, another clue, or… well, maybe another countdown? Who knows?
Gabe knows. Him and the kitty looking at the tri-buttoned gamepad at the bottom of the page…
Update: And barely a minute after I post this, Geoff Keighley tweets that Valve emailed him regarding these announcements:
Here we go: Valve just emailed me to say it will make three (3) announcements next week.
— Geoff Keighley (@geoffkeighley) September 20, 2013

DJ Judas
When Valve mention “3”, the world holds its breath.
TheDemocrodile
I wouldnt be surprised if Gabe and co referred to having “3” announcements as “We’ve got more than two things to show you but less than four”.
At this point i expect the rise of Cthulhu if ever they refer to that which shall not be named.
Nismo400R84
Also on the 25th AMD announce there new graphics cards
TheDemocrodile
I’m pretty sure there is no relation to the AMD reveal here, the smart money on the Steam Box is as a new fangled type of streaming device rather than an out and out console.
Nismo400R84
I wasn’t saying it was. I was mentioning the fact AMD are announcing the new line up on the 25th. The only way I would be getting anything to do with steambox is if it’s like Vita TV.
Steviepunk
Announcement 1:Steambox
Announcement 2: BTW Half-Life 3 is a launch title?
Not sure what the 3rd part of the announcement could be though. L4D3?
RocketSOL
3rd Announcement: “Only joking. HL3 doesn’t exist.” ;)
KeRaSh
That’s the only scenario that I can believe. Haha!
Starman
3 announcements?! Way to drag it out.
pdannysan13
Half-Life 3.
Rest don’t matter.
TheDemocrodile
An idea for a SteamBox could be something entirely OnLive in nature, simply sign into your Steam Account and play your games without ever having to undergo an install process again.
Then i woke up to the realisation that if OnLive has failed then i cant see a Steam version succeeding. Still given Valves resources i cant wait to see what they have in mind, bring on Monday!
PARKER94!
I loved onlive, just at that time i didn’t see the logic to splash out money on games i couldn’t actually touch physically.
I think really SteamBox will still require gaming PC’s and will just stream the image from the PC to the box in another room, hope im wrong though.
leeroye
An announcement announcing an announcement, nice. ;)