The title makes it sound as though this has been accepted into the Linux kernel when in fact it has not been. It is designed to work with the Linux kernel but it is in no way associated with Linux. FUD much?
Be Civil. See http://ycombinator.com/newsguidelines.html
So far as I can tell the kernel devs think it's harmful and A Bad Thing (TM), but not a violation.
Also as has been pointed out below, it wouldn't automatically make it GPL. It would make it in violation of GPL and releasing under GPL would fix the violation, but it wouldn't make it GPL.
No.
However, the customers who bought such devices could try sue for feeling mislead as a customer. If Samsung ever used the word free, open, or even linux, they might be liable under false advertising consumer protection laws. Keyword here is might, and is likely to vary based on where you live.
If enough people did this, samsung would likely feeling pressured to relicense the necessary (sold) kernel modules as GPL.