Netbooks are gaining in popularity, sure, but I think you'll find resolutions increasing again as the screen costs come down. 10.1 inches is plenty big for a real 720p screen. Honestly, I haven't developed to less than 800x600 since 1995. 2002's defacto minimum was 768 and to your point this has actually dropped 720. I don't see much hope getting devs to target 576. It is HARD to create a modern and useful UI for that size when the task bar takes up 40 pixels, the title bar another 30, the menu another 25, the toolbars another 33, the status bar 30, etc. Doubly so when you also don't want them to look stupid when someone uses a real computer with 1080 or 1200 lines of vertical resolution.
Personally, I think that Microsoft should just mandate a minimum of 720 lines of vertical resolution for Win 7 certification and lets move on. Anything smaller should be Windows, but rather some made-for-tiny OS with controls and UI metaphors that are likewise made-for-tiny.
I feel your pain, and as a developer I won't/don't go out of my way to make things tall. However, I'm also not going to sacrifice user experience to fit onto a screen that has less vertical real estate than my 1990, DOS + Windows 2.0, SVGA screen...