I'd have to say I agree - It's quite easy for someone to come up with the same idea as you and not even be aware that you exist(ed).
Blog posts and comments about my startup (http://FriendBinder.com) often think we copied FriendFeed, SocialThing or some other site though the reality is that those sites didn't exist when we started early in 2007 (or were in stealth at least).
That's life I'm afraid.