What differentiates Stack Overflow Careers from all the other job-board web sites is that candidates' CV's are linked to their Stack Overflow accounts, so an employer can get a feel for how smart a person is by checking their SO reputation and reading their questions and answers. They are also trying to avoid a lot of the annoyances that plague other job-search sites. It is also hoped that the association with Stack Overflow will attract the best candidates and employers.
I've set up my CV: http://careers.stackoverflow.com/kristopherjohnson. The process was pretty easy.
It costs $29 to enter your CV into the employee-search database, and employers have to pay a pretty steep price to search it. I think that's a good thing; it keeps things serious. (Note: You can create a public CV for free, but it won't show up in employer's searches.)
I'm not actively looking for a job, but if anyone wants to pay me huge gobs of money to play with cool stuf, I'm definitely available.