This blogger has a good post about the ASUS eee PC, and mentions that there may be GPL violations in the modification-and-distribution-without-source-publication of the asus_acpi kernel module. BusyBox is also mentioned. The author, Cliff, notes that the violation may have been negligence, but negligence doesn't count as an excuse when it comes to copyright infringement.
Its cool that people can and do hunt down these potential violations. Considering that most GPL-licensed copyright owners don't have the resources to police the use of their software, it has to be volunteer driven.