For the record, I now work for ClearChannel (a pretty big company), and it is by far the best place I've ever worked. You do feel the size of the company when it takes 5 separate IT guys to set up your workstation (hardware, software, email, phone, VPN), but as far as the actual day to day operations, I couldn't ask for a better environment. I am the only non-CS dev on the team, but I can hold my own.
Sure, all generalization break down upon examination, but I think any company that uses five people to set up a basic cubicle is pretty much a direct opposite of Google in corporate structure and culture. There are indeed companies, and large ones, where the autodidact can find a home, but it requires the kind of organizational looseness that an overwrought bureaucracy brings. In Google terms, this would be a lowering of the bar.
FWIW, I'm mostly autodidactic (have a CS degree but got it mostly in my last semester, after learning all the CS stuff while blowing off my physics major) and don't consider myself particularly social, and I've found Google to be a pretty good fit so far.
There are a lot of dominant social and professional conventions that derive from university experience, and I was using autodidact with the intent of excluding college graduates (or at least technical ones) in favor of the more archetypal bedroom geek.
It very much depends on how social and how much of a self-promoter you are. If you are willing to fight for the latitude to follow your own direction you will do really well. But it is important to be social as well, as you'll encounter more opportunities as well as your own sharp edges quicker.
I think the typical awesome engineer is just a shade too self-deprecating to even think it possible to get hired there.