Eric,
At the underclass event in Ft. Myers, all of those are verbal commitments. NCAA rules will not permit the signing of NLI's until the November early signing period of their high school senior years, i.e., over a year from now.
The time table for recruiting continues to accelerate year by year. My own son was very highly sought after, but didn't get his first offer until around Thanksgiving of his junior year and committed the following February. This year, I've seen all sorts of juniors who have committed over the summer and in the very early fall -- nearly all of them highly talented players who will end up in PG's top 300, let's say, but not just your top 50 or so as was the case just 3-4 years ago.
I think there has to be a limit on just how far back in time the players and the coaches are going to go to make commitments. Although people do sometimes change their minds, in practice it is very rare indeed -- at least now. If they start committing kids at age 15, though, I would think decommitments would explode and that would force people to rethink their timetables.
I do disagree with TR, because in the main these commitments hold up and you can see how a program's recruiting class is shaping up in ways that you couldn't just 4-5 years ago. And while I concur with TPM that in some cases there are special circumstances involved, my observation is that most of the very earliest commitments involve the programs that are perennial national powers trying to lock up the most obvious stud players. E.g., if you're a lefty throwing 90+ at age 16, someone is going to be willing to make you an offer. Whether you decide to accept early is your decision.
One thing kids need to remember, though, is that you still have to get through the admissions process and so the early commitment is not license to goldbrick it with the books. Also I've seen kids who have been nixed by admissions over behavior issues like getting suspended at school for one offense or another. Probably a very high percentage of decommitments that do occur involve things like DUI's, drugs, or other misconduct issues, even if those are not publicized as the reasons for the change of heart.