Maybe, maybe not. Often times that signing bonus is for a job that just put you into a higher income bracket... and if you weren't paying that higher bracket for much of the year, the entire overage ends up eaten in making up the difference between what you were paying in months 1-7 and what you now owe because of months 8-12. That has happened to me a couple of times.
But yeah, used to be you could get a $5,000 signing bonus and they'd be happy to give it to you... now, entirely different scenario, no bonus, no stock options, most happy corporate benefits are gone.