"This is going to play big."

So said an anonymous White House official according to AFP.
So far, what we know about the London airline bomber plot suggests that Al Qaeda is either behind the operation or at least the inspiration for the jihadists, some of whom had with ties to Pakistan.
The New York Times headline, "Arrests Bolster G.O.P. as Election Nears" sums up a large part of the GOP's strategy for this election:

Republicans seized on the arrests of terrorism suspects in Britain yesterday to bolster a White House campaign to turn national security issues to their advantage this fall, arguing that the nation needs tough Republican policies to protect Americans from threats from abroad.

AFP reports that Republicans are hoping to take advantage of the news of the London plot:

But Bush's Republicans hoped the raid would yield political gains.
"I'd rather be talking about this than all of the other things that Congress hasn't done well," one Republican congressional aide told AFP on condition of anonymity because of possible reprisals.
"Weeks before September 11th, this is going to play big," said another White House official, who also spoke on condition of not being named, adding that some Democratic candidates won't "look as appealing" under the circumstances.

I'm not convinced. There have been other terrorist attacks since 9/11, including the train bombings in London on July 7 of last year.
Four years and eleven months after 9/11, more and more people are seeing the war in Iraq isn't making us safer, despite Republicans' continuing effort to conflate the war in Iraq with the fight against terrorism. I've not heard anything to suggest that the plotters had any connection to Iraq.
The growing opposition to the war in Iraq is a long term trend and unlikely to be reversed by events elsewhere. For instance, the fighting between Israel and Hezbollah hasn't changed many minds about Iraq, despite the hope of some in the GOP that an expanding conflict in the Middle East serves their political ends.
So we we shouldn't be surprised that we are seeing the same tactics from 2002 and 2004. But as the Times reports, Democrats aren't shrinking from the argument:

But in a sign of how this campaign might be different, Democrats struck a tone notably different from the elections of 2004 and 2002, when for the most part their strategy was to try to turn the subject away from national security. This time, Democrats attacked Republicans as failing to improve airline security and, most of all, argued that the decision to invade Iraq had been a distraction that depleted United States resources and allowed the world to become more dangerous.
“The war in Iraq had nothing to do with the war against international terrorism, or very little to do with the war on terrorism,” said James Webb, a former Reagan administration official running as a Democratic candidate for Senate in Virginia. “It has distracted our attention, it has pulled our forces in, and we are now in a situation where we have 135,000 on the ground, which affects our ability to do a lot of things that we would be able to do otherwise.”

Former Virginia governor Mark Warner doesn't think the same tactics will work this year:

Republican wishful thinking notwithstanding, Tuesday’s vote was anything but a Democratic party repudiation of a robust and determined defense of this nation’s security. To the contrary, it is a call for a return to an American foreign policy that unites our friends and divides our enemies—and a call that will inevitably sweep through November’s elections.

Given the way things have turned against the Republicans, I expect that we will be hearing more of this for the next three months:

“Defeatocrats!” declared a statement issued by office of the House majority leader, John A. Boehner of Ohio, capturing the tone of Republican rhetoric as the news unfolded.

I just don't think it will work this time.