New York, N.Y.–That sound you’re hearing is the distinct twitch and gulp of some very nervous conservatives. No, it’s not 2004 they’re worried about. It’s 2008.

In the first two nights of the Republican convention in New York City, the stars, by far, have been Arizona Senator John McCain, former New York Mayor Rudy Guiliani, and California Governor Arnold Schwarzenegger. Their house-rocking performances not only exceeded expectations, they have led to pronounced talk about 2008. Whatever happens this November 2, there’s an excellent chance that one or more of these three will be on the next short list for Republican presidential nominee.

Despite a solid Sam Brownback here and a team-player Rick Santorum there, the Ahnulds and the Rudys are the ones who will be remembered the next time around. In four years, these Republican-convention wonderboys will provide the political buzz at the watercooler.

A political convention is always about more than the presidential race at hand. Operatives don’t just look up to the stage–they look to a party’s future. And with no Republican heir apparent in Vice President Dick Cheney–assuming Bush is reelected–this is a week about looking for the next guy.

In fact, before the stirring speeches of the convention’s first two nights, 2008 talk was already swirling in the air–maybe because GOP members with presidential aspirations haven’t been all that shy about networking the town. Stop-offs at delegation hotels and sit-downs with editorial boards have filled the schedules of our candidates-to-be. The long-term-focused Log Cabin Republicans are hoping to play the part of kingmaker; they honored Arnold Schwarzenegger on Sunday and also raised the possibility of a “President Pataki” to thunderous applause. (New York’s Governor Pataki, while not at the recognition-level of a Rudy Giuliani, is nevertheless a faithful Republican moderate with eyes on the White House.)

So, here we are. The nervous conservatives know a Moderate Fest when they see one. But this Republican convention has been most notable in that the mods in question have been uniters, not dividers. They’ve talked on the issues. They’ve been the consummate conservative team players. No gay marriage from Arnold. No abortion from Pataki. And so on.

This, of course, makes them all the more attractive as potential leaders within the GOP. But for the conservative right, this is the stuff of chills.

As one cautiously pessimistic social conservative put it: “Let’s not go punching out our chads for 2008 just yet. Rudy may give a good speech explaining why a conservative president should be reelected in 2004, but that’s a long way from proving that the tent is big enough to be held up by a left-of-center pole.”

Over two quick convention nights, the Republican moderates seemed to lift the canvas of that tent with the mere breath of their pro-Bush convictions. But in the years ahead, we’ll be back to poles and positioning within the GOP. Is it too early for conservative Republicans to sound the alarm? Perhaps. But a good amount of nailbiting just might be warranted.