Following up on Jim Dalrymple's thoughts, here's a good piece by John Gruber over at Daring Fireball.

It was inevitable that competitors would follow the iPhone’s lead, and it was inevitable that Apple would feel wronged when it happened. What I wonder about is whether it was inevitable that Apple would sue. Are they pursuing Samsung in court because Samsung is so clearly their most successful rival in the handset industry, or is it because Samsung so clearly copied — not merely followed but gratuitously copied — so much from Apple? I suspect it’s both — that it was the combination of Samsung’s blatant copying and mimicry of the iPhone’s trade dress, combined with their success, that has compelled Apple to fight them tooth-and-nail in court.