One word describes this lawsuit: Stupidity.
First of all, if this affects new iBooks, and Apple doesn't give a rats-behind, then yes, I can see where this is going. However, I don't think it is affecting new iBooks, therefore, making this lawsuit nothing short of ridiculous.
Here are a bunch of people complaining about iBooks as old as 2001 - 3 years ago - that may be defective. Why does Apple not possibly give a crap about these defectives now? Hmm, when I check the Apple Store, I don't see any iBook 600/700 models in their iBook section -- why should any company care about discontinued products? Apple apparently doesn't, and I wouldn't be surprised if any other reasonable company didn't, either.
I agree that Apple should of cared about the issue back in the year they were still selling, but to demand answers, money and whatever else nowadays is absolutly stupid. I realize still thousands of Mac users own these iBooks, and I know some resellers still even sell them -- but that does not, at all, make Apple have to care about a product, that is, even though still in use by many users, officially discontiued.
As far as I see it, Apple doesn't owe you iBook owners a single thing, regardless if the defect is "Apple-designed" or if the company knew about it. The iBook 600 is old - that's like someone filing a lawsuit against Apple for a defect in the Mac SE* in the year 2003 - just as stupid as this lawsuit. Not exactly the same situation as my example, but pretty close.
*There wasn't a defect in the Mac SE - it was an example.