Interesting post comparing the two. I'm not familiar enough with WP to know how extensive the similarities are, but it does make a good point about different OSs using similar design elements:
I personally don?t like to claim that one company stole an idea from another company; I have this stance, because I encourage companies to become better by implementing their variations of what is already available on the market. A personal motto of ?let the best implementation prevail?!
Here's the full post, if you're interested.