That is debatable. I don't think there is much question that they timed their release schedules to be shortly before those of other distros, then pulled in the features from other distros first, then did not correct users when they assumed Ubuntu developed said features. I haven't heard it much recently, but there was a while where Ubuntu fans were going on and on about the great Linux stuff Ubuntu developed, when really they had no part whatsoever in the development, it just timed things so it would be first to have the features. Then there was the case where they decided to bury all mentioned of debian deep in their technical documentation so there was no hint to users that Ubuntu was actually based on another distribution. Yeah, you could find a mention of debian six layers deep in the documentation in the 4th paragraph or something like that, but no user would find it unless they were specifically looking for it.
Originally Posted by kaczu
Of course none of those things are illegal, but I know many people did consider those sorts of things being "knifed in the back", since they were intentionally promoting themselves at the expense of the groups actually doing the work.