According to this  article in the Boston Globe, Gov. Patrick is considering a plan to make community colleges in Massachusetts tuition-free by 2015. As appealing as the idea is at first glance, I have to recommend against it.
First, I'll grant its obvious appeal. A cc without tuition will make it easier for students to graduate without major debt. (There would still be the costs of textbooks, activity fees, transportation, and the opportunity cost of potential work hours lost to class time and homework.) When students have to work a tremendous number of hours every week to pay for school, the time they can devote to studying is crunched. Many cc students come from modest income backgrounds, so even low tuition can be a real hardship. And the prospect of major debt is a real disincentive to enrolling, or to continuing to the four-year level. No argument on any of those points.
All of that said, though, I think the program would unfold as a slow-motion disaster.
The public K-12 system in Massachusetts, which doesn't charge tuition, has been reduced (in some districts) to charging school bus fees to stay afloat. If that's what full reliance on government funding brings you, I shudder to imagine the long-term impact on colleges if they drop tuition. The next time a tax revolt rolls around, I'd expect some demagogue to propose some seductively sweeping quick-fix across-the-board budget cuts that would absolutely eviscerate higher ed. (See TABOR, Prop. 13, etc.) Since the same people who lead tax revolts are also the law-and-order folk, you know they wouldn't cut police or prisons to make up for lost revenue; higher ed would be a sitting duck. We've seen that happen in enough states by now that you'd think we'd know better.
At least with tuition, there's an independent revenue stream. Yes, a too-high tuition level will freeze some people out, but a too-low (or nonexistent) tuition level will freeze everybody out when programs or even campuses are eliminated for lack of funding. What would almost certainly happen – based on what I've seen with existing programs in Nursing, which are terrible money-losers for cc's – would be long waitlists and/or lotteries to allocate seats. (Alternately, in the chalk-and-talk areas, you could go to all 300-student lectures with scantron tests. The 'learning outcomes' of that approach are depressingly predictable.) Excess demand coupled with a complete absence of a price mechanism will lead to all manner of silliness.
(I saw an example of that in the early 90's, when I briefly lived in Berkeley. Berkeley still had rent control at that point. Apartments were available at reasonable rents, but 'key money' or 'finder's fees' often reached four figures. Water finds its own level, one way or another.)
On a state level, replacing tuition with direct state aid would, all else being equal, replace federal money (Pell grants) with state money. Why a state would voluntarily leave free money on the table, I don't know. I imagine the taxpayers of Massachusetts – a long-suffering lot already – would find that one hard to swallow.
There's also the delicate issue of student attitudes. I work with some folks who have taught in systems in decades past, where tuition was either free or so low as to be effectively free. They've shared horror stories of students adding and dropping boatloads of classes with impunity, since it didn't cost them anything. 'Behavioral economists' like to talk about the 'sunk cost fallacy,' which is the habit of mind that makes us likelier to attend a concert for which we've bought tickets than to attend one for which we were given tickets, since having bought the tickets, we think of non-attendance as a financial loss. It's mathematically false, but psychologically true. I suspect the same holds true for tuition. Putting up some money – and it doesn't have to be much – creates a psychological pull that a true freebie doesn't.
Besides, free tuition would encourage the academic equivalent of the welfare queen, the dreaded “perpetual student.” These have mostly disappeared over the last few decades, but would make a quick comeback under this system, especially during recessions, when the opportunity costs are lower.
I'd also worry about any system that completely decouples funding levels from enrollment levels. (That might or might not happen, depending on the details of implementation.) Under that system, when the inevitable crunch hits, the incentive for a struggling college would be to get as student-hostile as possible to get its costs down to its aid level. This is easier than you'd think. Just use the DMV as the model for any student contacts, skimp on web platform maintenance, close off the occasional student parking lot, run too-few sections of required classes, and voila! This strikes me as a horrible outcome.
My suggestion to Gov. Patrick, if he wants to improve college access and is willing to pony up some money to do it, is to establish some sort of scholarship program in which the renewal of a student's scholarship is contingent on a given GPA (or some other easily tracked measure of success). To the college, tuition is tuition, whether it comes from the state or the student, so the college's incentives would be right. This approach would get around the issue of subsidizing slackers, since students who aren't academically serious would lose their scholarships. It would be much cheaper for the state than eliminating tuition altogether, and it would keep in place the infrastructure of tuition-charging to turn to when the next recession hits. Hardworking students from modest backgrounds would get the full benefit of a functioning college, which they probably wouldn't under an 'everybody free' system. Improve direct operating aid to the cc's a bit to get the rate of tuition increase under control, by all means, but don't get rid of tuition altogether. It serves too many purposes, and would leave colleges grotesquely vulnerable to the next recession or shift in the political winds.