A grid of icons isn't exactly new. Palm did it before Apple. Windows 3.11 before Palm.
Apple's Newton OS came three years before Palm's Pilot. Apple's Mac System came 8 years before Windows 3.11. They all used grids of icons, it's part of the desktop metaphor. If that were the only thing Samsung copied, I doubt they would be getting sued now.
HTC also doesn't use Google's stock Android UI. It uses its own Sense UI [2], which it also put on BREW and Windows Mobile phones.
Other Android handset makers also created their own custom UIs. Motorola has Motoblur [3], SonyEricsson has the 'UX' platform [4].
[1] http://en.wikipedia.org/wiki/Touchwiz
[2] http://en.wikipedia.org/wiki/HTC_Sense
[3] http://en.wikipedia.org/wiki/Motoblur
[4] http://www.xperiax10.net/2009/11/18/se-launches-nexus-ux-pla...
Yeah, there there's too much of a difference (IMO), especially as the device itself looks substantially different. Android, I think, looks plenty different to avoid the suit - the Galaxy S in particular, though, doesn't. Not sure what their aim is there.
Samsung's design isn't just derivative, it's more or less a straight copy. Microsoft illustrates that there's no necessity built into the medium that requires an iOS-like interface.
Apple may forever be chasing "look and feel" violations in vain, but I think they have a point when they say that Samsung's interface is basically just a rip off.