That's the point of the compendium and WotC hawkishly putting a stop to various sites that have sprung up using WotC D&D IP to create competing (even if free and not as good) DDI-esque interfaces.
If that's the case Power Card Viewer on appspot would also be in trouble. It was one reason why I didn't include Power Cards, I wasn't sure how WotC would react to my app simply having a feat/feature/item database let alone power card data. I wasn't going to go through the trouble of manually putting thousands of powers into the database to have WotC tell me to cease and desist. I would have wasted hundreds of hours of my life.
I built the app with the idea that it would make D&D 4E even more accessible to people by allowing them to save time by rapidly filling in all the details for them. My app still very much requires the D&D books. It hardly enforces anything. For example, a heroic tier warlock *could* pick a an epic tier fighter feat. Or a bard could pick a wizard paragon class. The app doesn't show the prerequisites for anything and unless you know the name of the feat or item, you're going to have a hard time building your character by picking them at random.
So technically WotC wins big time. Character4ge users will still need to have the D&D books to look up which feat they can use. If WotC decides that my app crossed the line (IMO it hasn't), it's their loss (and mine I suppose). I'm not robbing them of anything...I'd argue that I'm potentially increasing their customer-base.