Imitation is the greatest form of flattery.
That being said, I agree - don't be mad. People copy - either intentionally or subliminally... they see something they like and they imiate it. This is how it was done in the beginning, how it's still done today and how it always will be. As long as it's not an exact copy I wouldn't sweat it. Just think of it as everyone else just catching up to you, but you're lightyears ahead - probably working on something new already and moving a big step forward, while they're busy just copying what you did months/years before.
It's part of the evolutionary process of the 'Net... it sucks - but that's how it works.
