Just to finish this debate off; Steam runs a program where if you’re selling an alpha / beta version personally (the pre-payment business model), as long as the Gold 1.0 release is done at the same time as the Steam release, keys can be given retroactively, at no charge to the development team. It was part of the pre-Green Light arrangements, probably out of date now (although I do notice that games such as Krater & Under the Ocean follow the same patterns).
I’ll not presume to know Cliffski’s actual deal with Steam, but GSB (and at least 4 of the DLC) were available 1.0 long before going onto Steam, which means he probably doesn’t enjoy that deal, and thus it doesn’t exist. A similar game stance is S.P.A.Z., which came to Steam very late, and the beta version I had (pre-Humble Bundle, picked it up there again) never had Steam keys attached retro-actively.
Quick translation: when an indy developer sells their soul to the dark over-lords of distribution such as Steam, they have to pay a % of sales price to Steam (and, indeed, sometimes cannot even argue about the % cut on sales, which is why the Steam Sales are a bit of a double-edged sword to small dev teams, but I digress). This is the price of mass-market impact; if you support Indy devs directly, of course they get a full % of the cash. However, you have to be in the market to track / follow and be knowledgeable about which Indy teams are producing good product, and those who aren’t (cough WarZ ~ who if you’re in the biz have done more to screw over quality indy teams than anyone else in 2012, and you should shun them totallycough).
There’s no friction: it’s simply a business deal between Positech Games and Steam; if you don’t buy the product through Steam, they don’t get their % cut, so never expect keys. There are exceptions to this rule, but largely it holds. Any Indy dev giving keys out retro-actively are usually having to pay Steam for said keys, so are taking a hit from their own pockets, fyi (which is why “gold” alpha support of packages are usually given keys and so forth, because the devs are nice & appreciate the support, from their own pockets, so don’t thank Steam).
In this case, Steam activated GSB was available from a Humble Bundle (and so, extremely cheap), and the DLC activates with only minor trickery, so no-one has lost out at all. At this point in time, if you’re not either buying direct or at least dropping $15-20 on each Humble Bundle just as a statement, you’re either under 18 or don’t deserve to enjoy quality Indy games. It’s that simple (and yes; I drop $20 - 30 on each Bundle no matter if I’ve already got the games, to support the industry).
Just remember what happened to THQ, even with their Bundle ~ small indy teams like Positech have no-where near the same salaries or benefits those people had, so support them & don’t grumble. THQ were dropping upwards of $25,000,000 on a single game, for reference. Just marvel that mad geniuses make quality games and don’t just go and work for EA on the 2013 Sports Title de jour, and enjoy their visions of Games
Full Disclosure: I might know what I’m talking about.
 Both very decent efforts so far, and doing the whole “Alpha / Beta pre-payment model” correctly, imo.
 At the moment, I have about ~13 alpha / beta paid subs on indy games out there; I’d say at least 7 of those you’ve never heard of, and certainly haven’t hit the Green-Light radar by a long way. Probably at least 50% of them will die out, but all are quality / have their own unique Game builds.
Oh, and btw ~
Best game you’ve never heard of / played: Precursors. If you get the English Translation mod (because, yes, it doesn’t have native English release) + various unofficial add-ons, it’s the best SF RPG you’ve never heard about, with modern  graphics and very well built, with huge amounts of quests / skills etc. 20+ hours in, and suddenly you realise it’s got a fully fledged space combat / trading game in addition to the surface world RPG stuff, and you’ve 4 more planets to explore, with full Ethical choices (you know, those things that got taken out of Mass Effect for being “too confusing”).
The team were from Kiev, if you need to narrow your searches down - and you’ll have to grab it from the Russian versions of Steam, but, like System Shock, it’s something you really should play if you consider yourself a “gamer”. Just don’t expect glowing arrows telling you were to go next, or holding your hand