I recently came upon an Ubuntu 10.04 PPA with Intel GMA500 "Poulsbo" packages which you can use to get everything working. Well, almost everything as only 2D will work, 3D unfortunately is not supported.
This PPA aims to port the Mandriva patches for the psb driver to Ubuntu 10.04 Lucid Lynx in order to enable GMA500 support in Xorg 1.7.x.
Before adding the PPA and installing the packages, please note that I don't own an Intel GMA500 graphics card anymore so I didn't test this!
Add the PPA in Ubuntu 10.04 Lucid Lynx and install the Intel GMA500 Poulsbo packages using the following commands:
sudo add-apt-repository ppa:gma500/ppa && sudo apt-get update
sudo apt-get install poulsbo-driver-2d poulsbo-driver-3d poulsbo-config
Then reboot.
Note: because 3D won't work, Compiz will be removed!
Specific netbooks instructions
On Asus and Sony Vaio add the following workaround:
-run this in a terminal:
sudo nano /etc/default/grub
And find the line that begins with "GRUB_CMDLINE_LINUX_DEFAULT" and modify it so that it looks like below:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash mem=2000mb acpi_osi=Linux"
Then update your GRUB:
sudo update-grub
On Acer 751h, to fix battery status, add this to startup (System > Preferences > Startup Applications):
cat /proc/acpi/battery/BAT1/info