That is, they try to tip us off on who'd they'd put on the Supreme Court.
I'll analyze the language later this evening, but I thought you'd enjoy chewing over it.
ADDED: As I expected, these statements are pretty much the same, but there are some subtle differences. McCain goes first, so I'll list the 4 basic things he does, and then we can see how the others deviate from the McCain model:
1. Assert a strong belief that judges should only interpret the law as written and not usurp the role of the legislature by declaring that the law is what they want it to be.
2. Imply that you nevertheless expect them to reach outcomes that you like by pointing to the outcomes you expect the judge to reach.
3. Refer to separation of powers and federalism.
4. Invoke the name "John Roberts" and one other Justice who represent the judicial ideal.
Romney omits #2 (the most dubious point), but lest conservatives think he's not going to give them what they want, on #4, he invokes John Roberts and adds not just Samuel Alito (McCain's other Justice) but also Antonin Scalia and Clarence Thomas.
Huckabee omits #2 and 3, and, like Romney, he names all 4 conservative Justices.
(I'm ignoring Ron Paul, who seems as though he might want to repeal the 14th Amendment.)