To me, it means an entirety new interface, and in the case of a hybrid, plenty of forked code to support it. So does the developer charge a higher price for the hybrid to everyone because it took 59% more work to build it for both, or does he put out two versions? Charging for each?
Agreed. A tablet UI and a phone UI (or, more to the point, multiple UIs dependent on the screen size or even more ideally user preference) is more work than two simple monolithic user interfaces written separately. Making on-screen assets optional is a whole different level of complexity.
But in the Android world, with screen sizes ranging from a couple of inches to 10 inches, I think we're going to need to see a lot more of this development, and not just a "phone" / "tablet", but more granular levels of detail for some applications.
Thankfully, the majority of applications really can't benefit all that much from this. When I'm running an "exploration" type mapping application, I'm almost always going to want maximum mappage with everything else pop-in or menu driven. Most applications serve a specific purpose, and while a map-and-list view on GasBuddy would be nice, honestly, I'm not going to be using it for sustained enough periods of time to care - it's usually a "I'm about to head to work or home and I need fuel; which route should I take to go by the cheapest station? 'kthanksbye", or "I just drove by a station and I have the prices in memory, I'm at a red light, what's the FASTEST way to get those prices in the database before the light turns green?" interaction.
But there are a few apps where I can certainly see benefit to multiple user interfaces depending on screen size, and even the purpose for which I am using them at the moment (when I'm planning a trip in Google Maps, I want maximum options. When I'm DRIVING that trip, I want a simple map preview, my next two turns, my current speed, and a traffic warning indicator). And for those apps that benefit from multiple views, I'd gladly pay developers extra for apps that take full advantage of my 640x480 7" Pantech Novel, my much-higher-resolution but smaller-screen Thunderbolt, and my Nexus 7.