It is just slightly bigger than the old one... and that screen is goood..
Click to see the video
So far i really like it.
It's has all the same cpu/chipset/harware than 701, but with the 8.9 inch 1024 x 600 screen, 1GB ram, 1.3mp cam and 8GB SSD.
Option for Linux or XP. Available mid April at 399 euros with Linux.
UPDATE: I posted a follow up on it
Asus Eee PC 900 Details, Links and News
Asus Eee PC 900 Press Release
Tuesday, March 04, 2008