Active Steam users will likely find the first half of this post to be a bit on the old hat side, but we soldier on: Valve's flipped the switch on a new and improved beta version of Steam. If you've already got a Steam account, you can download the new version by hitting up this page. The beta adds all kinds of nifty stuff, like accessible lists of what games your friends have downloaded (along with their personal stats for each title) and some new ways for you to sort and organize game libraries. There's also cross-game achievement tracking -- and Valve's finally done away with Internet Explorer rendering, swapping it out for the friendlier open-source WebKit engine.
But, that's not all! Our sister site Big Download was cruising around the new achievements interface and noticed that Half-Life 2 and Half-Life 2: Episode One now have achievements listed under them. As you know, Half-Life 2 released right around the time achievements were finalized, so it never arrived on Steam with them. Sadly, there's no news other than the icons -- which look a lot like those found in the Orange Box on Xbox 360. We'll be sure to keep you posted.
Source - Half-Life 2 achievements spotted
Source - Steam beta update news