I'm not sure, but I think the original verdicts will have to be overturned before a plea deal can be made. Usually plea deals are arrived at before a conviction comes down. Legal help here, please!
What I've heard is that the no lo contendere plea will free them but not exonerate them. Some people might believe that they're guilty because they pleaded no contest. However, if they are truly guilty and in prison, why would the State of Arkansas permit such a plea? To me, the fact that the State is willing to entertain such a plea means that they know they don't have a case and they're trying to save face.
The Alford plea is a little more complicated. It means, if I understand what I've read, that they will maintain their innocence but concede that there is enough evidence that a jury might find them guilty at a retrial. Again, they will be freed, but some people will still believe them to be guilty.
From what I'm reading, what will happen tomorrow (really later today) will free but not exonerate the three. Not a perfect ending, but, if I had been imprisoned for 18 years for a crime that I didn't commit, I'd probably take the deal, too. I do believe that they will not have a criminal record for this, so that's something. PLEASE, SOME LEGAL MIND HERE CORRECT ME IF I'M WRONG!