With that in mind it seems like there is a market for a git replacement for these huge repos.
It is my guess (though I have no proof) that most places with particularly large repositories have lots of binary files in them. It's hard to get a 15GB repository if you just have text.
This sort of thing suggests a centralized check-in/check-out model, because binary files are difficult to merge sensibly, and nobody wants to spend terabytes of hard drive space storing the repository locally. And your centralized check-in/check-out needs, whatever scale they might be, are probably tolerably well served by one of the existing solutions.
15 gb is a tiny, tiny repo. I have a 7 tb repo "here" (really, spread amoung various drives, servers, S3, etc). :)
I think they are probably on par with craigslist in profits per employee (i.e. much higher than Google or Facebook. Interestingly I think Facebook has about 1/10 the employees of Google with 1/10 the profits -- off the top of my head feel free to correct -- so I don't think they blew it out of the park with their IPO filing).
If I were to make a snarky comment it would be that Git is for poor people and Perforce is what you use when you grow up. That's not an even remotely reasonable statement, but it does have a teeny, tiny hint of truth to it. :)
Perforce is a great system, but it's showing it's age by now. I think there is probably room for someone to make another product in the high end space and make boatloads of cash from big companies, but it's not easy.
Care to elaborate? Do you mean in terms of distributed -vs- centralised repos?
Another part of it is working disconnected -- with so many people coding on their laptops that's actually a pretty common use case.
Also the lack of need to do sysadmin work on git/hg is really nice. I used to run the free Perforce server a long time ago for myself, but it was annoying to do the backups. With git or hg you get whole-repository backups for free.
The "big repository with all dependencies model" has its drawbacks but it's interesting that facebook finds a lot of use for it, and that git is unsuitable for it. Perforce is probably still their best choice in that case.
Later this year they are adding p4 Sandbox which allows for disconnected work. When that is complete and working I'm honestly not sure what advantage git will have left other than being free.
I've used for 10+ at work, and it's easy to explain to anyone how to use it (from production to artist, and coders).
It has it's gotcha moments, but I haven't seen better. We normally go by 50-100GB depot, and then often whole branches of the game copied.