It's called divide and conquer politics. McCain has the base locked up now, so it's smart for him to peel away some undecided Hispanic voters. Keep in mind that Hispanics loathe Obama (blacks) and supported Hillary over him.
McCain's not going to push amnesty unless he wants to lose the sudden support he's gotten from conservatives over Palin. Think of all the money McCain has reeled in from the base. But for now let's worry about voting in McCain and then we can keep an eye out for any amnesty shenanigans later.
That's my whole point. McCain's choice of Sarah Palin is what solidified the base and caused the money to start rolling in, not pandering for illegals' votes.
All this does is give Obama ammunition to point out that there's barely a centavo's worth of difference between his stance and McCain's. And Obama won't even have had to spend a plug nickel to get that message out.
This ad is not about immigrants, legal immigrants already have a path to citizenship. This ad is about legalizing ILLEGAL aliens!