It's not organized like that. Rather, there are perhaps 100
public-facing products. And then each product has lots of individual features that have teams working on them. For example, I work on Google Search, but the actual projects that I've worked on include Wonder Wheel, the left-nav, the move of all the properties (books.google.com, video.google.com, etc.) to www.google.com, the May 2010 visual redesign, the occasional doodle, some consulting on last week's visual redesign, and Authorship. If you mention those to most people, they go "huh?" until you point it out to them, because they just think of Google Search as one integrated product.
And then there's the infrastructure supporting that, which is technically fascinating but never gets any public recognition, because it's all confidential.
If your goal is to be famous, then yes, this is mundane work. But if your goal is to work on interesting technical challenges, it is a lot more challenging and fascinating than slapping together a RoR app.
I'll point out that the startup world is like this too. For every Mark Zuckerburg on the cover of time magazine, there are a dozen DropBoxes and Herokus that get some acclaim within their niches but are unknown to the world at large. And then for every Heroku, there're a dozen FreshAddress.coms or Bingo Card Creators that have a very tiny niche that can support their founder but is virtually unknown outside their customer base. And for every BCG, there are a dozen startups that fail completely and nobody knows about.
One thing that really surprised me about the real world was just how deep the iceberg goes. I was an outsider until I was about 27, first as a student, then as an employee in a startup with big dreams but small successes, then as a founder in a startup with big dreams but small successes. People know the Zuckerburgs of the world because the media write about them; the media write about them because they need larger than life personalities to get people to buy their magazines.
The "celebrity programmer" is a creation of the media. Just look what happened with Google+ and Andy Hertzfeld. He worked on one aspect (UI) of one feature (Circles) of one product (Google+). He is just as much of a peon as the rest of us, but because he has a prior track record and people love a good hero story, somehow that got blown up into "the lead designer for all of Google+". Andy, to his credit, didn't take the credit and shared it with all the people who were actually involved in creating the UI for Google+.
(Actually, I worry sometimes that listing projects I've worked on here will result in the same thing happening, since I'm at least a recognizable personality on HN. I was not the primary developer for Wonder Wheel - the guy who was is a kickass developer with his own startup now. I was not the primary driving force behind merging all properties into one - the woman who was is now working on a cool data analysis problem in an overseas office. I was the first engineer on the 2010 visual redesign, but I was not the tech lead, and many many other people helped out. I'm not the primary doodler, I've only done one or two when that guy was busy. I'm one of three co-TLs on Authorship...I'd like to think I contribute a lot, but many other people contribute a lot too.)