Thank you to happymac10 for the information above. This is a short addition to the info.
Be aware that there is no "official" repair or replacement program at Apple for these out of warranty computers. You will likely be told that it will cost approximately $375 to replace the LCD panel. That's the "official line" from the frontline Genius Bar employees. Unfortunately, due to their level of authority, you're unlikely to get a free or discounted repair.
Next up the authority chain will be a Genius Bar manager or supervisor. They will repeat that there is no recall or repair program, but will likely explain that there is a technical or engineering investigation notice in their database regarding the vertical lines in G5 and early Intel iMacs. They might also tell you that what's on Apple's user forum or other forums doesn't reflect Apple policy at the present.
BTW, all of what the folks at the Genius bar are saying above is absolutely 100% the truth, no distortion, no misleading statements or bad behavior.
You may feel that you are at an impass, however as mentioned above, it is also true that Apple managers have what can be best called "leeway" or "discretion" in this matter. Being calm and sincere about your position will likely help you in this "case by case" decision that they will make.