Is there a point to this, other than trying to provoke?

S. Korea launches massive military drill
Largest joint firing exercise of 2010

South Korean tanks fired artillery and fighter jets zoomed by to drop bombs Thursday in the military's largest air-and-ground firing drills of the year — a show of force exactly a month after a deadly North Korean artillery attack.

The drills took place at training grounds in mountainous Pocheon about 30 kilometers from the Koreas' heavily fortified border.

The drills are meant to signal South Korea's determination to demonstrate and hone its military strength at the risk of further escalation with North Korea.

During a separate visit to a front-line army base near the Korea's eastern land border, President Lee Myung-bak vowed a strong response to any new attacks by North Korea.

"I had thought that we could safeguard peace if we had patience, but that wasn't the case," Lee told troops, according to his office. "Now we should have a strong response to [North Korea's provocations], so that we can safeguard peace, deter aggression and prevent a war."

In Pocheon, tanks fired artillery rounds as they raced down cold, foggy mountain roads. The boom of cannons echoed through the valley and the hills erupted in smoke. Rockets streamed through the air and slammed into the side of a hill as helicopters overhead fired at targets and F-15 jet fighters dropped bombs.

The drills lasted less than 45 minutes and were the armed forces' largest joint firing exercises this year. They were also the biggest wintertime air and ground firing exercises in terms of the number of weapons mobilized and fired, government and army officials said on condition of anonymity, citing department rules.

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http://www.cbc.ca/world/story/2010/12/23/south-korea-military-drill.html

"a show of force exactly a month after a deadly North Korean artillery attack"

I think that's the point.

I get the impression, not just from this drill but also from the general reaction to the shelling, that the South is tired of North Korea constantly scratching at them.  The shelling was just the latest in a long series of attacks by the North and, in each case, South Korea has been compelled to be restrained in their reaction.  For the North, of course, their actions have been pretty profitable.  They do something stupid and other countries, especially the U.S. and China, throw all sorts of goodies their way to calm them down again.  I think the South's military exercises were designed to serve notice on both North Korea and the rest of the world that they're not going to be the punching bag anymore.

Since nothing much is achieved, both sides are being foolish, IMO.