How much do tax credits for employers help?

A recent article in the Wall Street Journal looked at whether the tax credits being proposed by President Obama will actually spur hiring.  Since employers make their hiring decisions based on business needs, there are questions as to whether these offsets would lure anyone who wasn't already planning on hiring.  As one employer noted: 

"Giving me a tax credit if I hire somebody? That's not a really big incentive for me," said Mark Sincavage of Sincavage Corp., a Blakeslee, Pa., commercial excavation company that employs four. "We need customers in the door."

Mr. Sincavage, who has laid off two workers during the downturn, said a credit of $3,000 -- the number he expects -- won't help if he can't come up with the rest of a new employee's salary.

It got me thinking about the tax credit employers receive if they hire ex-offenders.  Under current law, companies are entitled to shave $2,400 off their federal  tax bill in return for employing certain targeted groups of job seekers, which include former felons. A handful of states ,as noted here offer additional credits.   But most re-entry professionals I've talked to,say these credits on their own aren't much of a selling point.  As OAR's Nathaniel Harris( who talked about what employers are looking for  in an earlier post ) noted, "It's nice that it (the credit) is there, but it really doesn't help unless they were planning to hire the worker already."

How about the rest of you?  Has anyone had success using the employer tax credit as a selling point?  At what point do you bring it up?