>Real IP lawyers cost real money. Anyone working pro-bono on something of this size probably isn't qualified to work on it. So gather some (money) if solid legal ground is a long term goal. It would seem a shame to go through all the work and hassle to find out later, when it really mattered, that something wasn't done right. I'm not sure size, I'm assuming you mean the size of the code base, is entirely relevant here. You just need someone who can accurately explain the history of MAME/MESS development, how the license changes have been handled previously, and figure out what needs to be done to move in the desired direction. Sure, maybe that's not as good as paying gobs of money to have a lawyer sort through it all by themselves but I think it would be better than a bunch of software developers' legal advice.
In Aaron's initial post he laments the situation of having a license that wasn't written/verified by a lawyer. So why forge ahead with a plan equally unverified?