Since Android supports styles and it's good practice to use them (similar to CSS), I made a new style and applied it to 3 buttons.
The Layout builder in Eclipse did not register the changes and either broke (showed nothing) or didn't apply styles at all.
After running the app in the emulator, styles are correctly applied.
So is there something I'm missing or the Android plugin doesn't support styles?
It appears that the Layout Builder in Eclipse is only good for a rough layout. Things like gradients won't render, or even resized images in a ImageView aren't displayed correctly. Simple things like a rounded corner causes the Layout Builder to fail to render anything at all. Hopefully Google will improve it in the next ADT release.
Unfortunately, third party editors like DroidDraw and Layout Editor for Android support even less features.
Confirmed as of 6/15/2010.
The irony is that not even the provided SDK examples render in Eclipse's layout preview.