It's easy to think that careers.SO is designed to be monster.SE, but it's not.
I've seen stated multiple times on SF that SE sites exist to drive traffic to the careers site, so I've always taken it for granted that it was meant to be a general purpose career site. Makes sense, so I had no reason to question it further in my one year of being on SF. On second look though, the assumption that it's a careers site for SE in general is incorrect.
If you've been on SF long enough, you've probably gotten one of the invites to the careers site. I've gotten one too. But look at it more carefully: "In recognition of your contributions to Stack Overflow" I wrote that off as auto-mailers that haven't been updated to use the StackExchange verbiage, but on further research I received that within 30 days of answering a question on SF that was migrated to SO.
When you actually look careers.SO though (particularly careers.SO/about), everything about it that is not user submitted content points at the site being marketed directly at programmers. The fact that other professions can get jobs there appears to be a happy coincidence that the SO owners benefit from.
Now, I could be wrong, but before you downvote, please drop a comment linking to something on the careers site that is not marketing it as a site for programmers. Tags, job postings, etc. don't count.
This is a great question, and I think there's more than enough room to grow the marketing for careers.SO in a direction that is more inclusive of system administration, particularly since it's already being used by them. But don't confuse who it's exclusively marketed to, and the people who are finding other uses for it.