In fact, that's an understatement. They're pissed. Really pissed. So much so, they want Sony's PlayStation 3 and Bravia TVs banned in the US. Why? Something to do with Blu-ray patent infringements.
According to Eurogamer, LG claims that Sony is infringing four of its patents that relates to "certain electronic devices having a Blu-Ray Disc player and components thereof". The PlayStation 3 is explicitly referenced.
Hilariously, Bloomberg reports that LG's claims are revenge for cases brought against them by Sony in December. Corporate warfare. How silly!