When the iPad came out, it had polish and the market to itself. This allowed it to grab a surprising toe-hold in a field that many thought futile. Android 3.0, by contrast, comes to market with a bit less polish and facing stiff competition. The field is no longer empty- Developers must decide whether to focus on Android, WebOS, iOS etc.
The iPad 2 builds evolutionarily on its first-to-market experience... Faster, but with no changes in the physical layout. As a result every iPad 1 app looks as good on the iPad 2 as it did on the original. If you develop for the iPad, you shoot for one resolution (1024 x 768) and one ratio (4:3). While there isn't a guarantee, future displays seem sure to maintain the same 4:3 aspect ratio with a doubling or tripling of resolution. In other words, the transition will be no more difficult than iphone 3 to iphone 4. Screen elements will be no larger or smaller... just the same or clearer.
Because Google doesn't control the hardware (for better or worse) it can't give the same guarantees. Thus, developers face multiple resolutions, e.g., 1024 x 600 (Galaxy Tab 7 and Viewsonic Viewpad) vs. 1280 x 1024 (Galaxy Tab 10.1, Motorola Xoom) and, at the same time, design for different aspect ratios, e.g., 16:9 or 16:10. This will only get worse when Ice Cream Sandwich throws smart phones into the mix. So... assuming you KNOW you're target audience is running a compatible version of Android... what resolution and aspect ratio do you go with? If you let Android do the corrections... can you expect your app to display with the polish you designed into it? The iPad's 4:3 aspect ratio may be limiting and imperfect... but its constancy allows design to move forward with certitude. If you're spending time and money to develop for a platform, you want to deliver something that looks good now, will look good later, and does so on tens of millions of machines.