It actually will. There's a lot of things we weigh the contextual job ads with. A lot of it is the (public) code you write and the location on your public profile.
We do ask that people explicitly opt-in for the ads (available for hire checkbox). One of the decisions we made while trying to weigh connecting jobs with job-hunters and not becoming an advertising company.
I'm not "available for hire", yet I like to see what companies are offering jobs in my area. Is the checkbox going to be used for more than just showing ads?
Right now, no. In the future, yes. So if you're willing to keep an eye on our blog (we'll warn you before we make this info public) you can check it. Or you can just search on the jobs site itself — http://jobs.github.com
We do ask that people explicitly opt-in for the ads (available for hire checkbox). One of the decisions we made while trying to weigh connecting jobs with job-hunters and not becoming an advertising company.