Ultimately, I think it's a vicious circle. Ex-cons are discriminated against because people assume they will re-offend, leading them to be stuck in dead-end jobs and very likely to re-offend...which society then uses as evidence to continue the trend of not hiring them.
So they can get jobs just they are not good jobs, so they are working. What do people expect after being convicted of a felony to walk out and say fine give me a good job over this person of the same age and background that was not in prison? The world is not like that employers can hire who they wish and its hard once your convicted of a felony that is life as it is your going to have a far harder time of things. In Florida you can't even enter several licensed professional like Cosmetology if your a felon that is what it is.
It may not always be fair but why do you expect an employer to take a risk on a ex-con when they should be free to hire someone with a clean record?
See, that's exactly the attitude that DarkStar is talking about that causes the proble. Why the hell should a burglar or mugger or embezzler be banned from being able to style hair? That has nothing to do with their crime or their punishment, just a attitude of "once a criminal, always a criminal - scum like that doesn't deserve to live decently like the rest of us" (not putting those words in your mouth, but it's a fair generalization of a lot of 'tough-on-crime' attitudes). And that's when the vicious circle starts - you as a hypothetical employer reject a hypothetical ex-con's job application solely on the grounds that he's an ex-con, no knowledge of what his crime was; he has this happen over and over, decides that since no one is willing to believe he's reformed, he might as well start stealing again, because clearly he's a no-good dirtball.
There should be a chance for them to at least work their way back into a decent job. If someone can even just support himself on a legitimate job, he's that much less likely to fall back into illegal activities - and isn't that what society as a whole wants?
It's like that story (and movie) Minority Report, the one with Tom Cruise where psychics are used to detect 'pre-crimes' and arrest criminals before they commit a crime. Felons with a record are permanently stained, and end up being prematurely convicted of a crime they haven't even committed yet, and might never commit - except that society has already decided they will re-offend, and bars so many doors to them that re-offending becomes the only way they can support themselves.
@ADarkStar: If I'm quoted, I'd prefer it be anonymously. With that caveat, go ahead.