The UI in Android Honeycomb is very different. I'm looking for things that have changed that would be of interest to developers. Google hasn't updated it's UI guidelines yet, so I am trying to find this stuff out by inspecting the layouts. I am mainly interested in dimensions of icons and new types of views.
The action bar height is 56dp (?android:attr/actionBarSize). It seems that the menu icons are 32 x 32 dp now, they were 48 x 48 dp before. Since they are in the action bar, they have a lot of padding around them. The size of a menu icon with padding is 64 x 56 dp. I needed this since I was trying to put a ProgressBar as a menu item.
Anything else change? Also, I'm interested in the size of some common UI patterns, like the widths for a list/detail layout like the mail client.
You might want to check out the latest Icon Guidelines as well as the section on Metrics and Grids.
Also, you can see details about the Action Bar and other things that are new to the platform.