John Gruber on the always interesting site Daring Fireball has posted a terrific, well-written response to critics who claim that Apple has unfairly stomped on the Konfabulator product with the new Dashboard software.
John's essays are thorough and a pleasure to read. In this case, I find myself thoroughly agreeing with him. Apple saw an idea that had been implemented in various ways throughout the last 20 years, most recently by Konfabulator, and came up with a new, original, and better implementation of it.
For more of Apple's perspective on this, read the perspective of one of the Safari developers.