"No person or entity associated with this film received payment or anything of value, or entered into any agreement, in connection with the depiction of tobacco products."
In other words: Some of the characters smoke in this movie, but that was our choice. The tobacco industry didn't pay us off.
According to the site Smoke Free Movies, which makes some excellent points but tends to go overboard (they think any film with smoking should automatically be rated R), the disclaimer is a recent addition to Warner Bros. products. It started appearing on Warner DVDs of movies that contain smoking at the beginning of 2008, and was added to smoky theatrical releases this fall. Gran Torino was the first time I'd noticed it, but I don't always stay for the credits.
The site also reports that Universal Pictures (at the behest of its parent company, General Electric) has started including a somewhat weaker disclaimer on its movies that contain smoking: "The depictions of tobacco smoking contained in this film are based solely on artistic consideration and are not intended to promote tobacco consumption." Note that they don't say they weren't paid off by the tobacco industry, only that they didn't intend for it to encourage people to smoke.
The reason this is a big deal is that for decades, the tobacco companies DID pay for product placement in films. Eileen Heyes' book Tobacco USA notes that Philip Morris paid about $42,000 for Lois Lane to smoke Marlboros in Superman II, and that Sylvester Stallone got half a million bucks to use Brown & Williamson (now part of R.J. Reynolds) tobacco products in five films in the 1980s.
Congress started to crack down on the practice in 1990, and Big Tobacco now claims innocence. But they claimed innocence then, too, even though internal documents proved otherwise; as Smoke Free Movies points out, why should we believe them now? That's why they say the Warner Bros. disclaimer is necessary -- to certify to the public that nothing shady is going on.
Assuming we can believe the disclaimer, I actually do take some comfort in knowing that Clint Eastwood's character smokes in Gran Torino only as an artistic choice. It makes sense for the character, a grizzled old Korean War veteran, to be a smoker and tobacco-chewer, and his health problems figure into the story. It would be disappointing if Eastwood had included that detail only because some tobacco company suggested it, don't you think? As for how much Ford paid to have its Gran Torino figure so prominently, well, that's another matter.