No Plymouth on Ubuntu 10.04 Netbook Edition ?

sudo apt-get install v86d; sudo hwinfo --framebuffer

This will generate a range of resolutions that are supported for boot

Next run:
gksu gedit /etc/default/grub

This is the line you have to find and REPLACE
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
with this
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset video=uvesafb:mode_option=1024x768-24,mtrr=3,scroll=ywrap"

NOTE: I used 1024x768 because it's the maximum resolution my laptop can afford in bootup stage. You can use what's suitable for you. 24 is the colour depth.

In the same file, look for the following line
#GRUB_GFXMODE=640x480
and replace it with
GRUB_GFXMODE=1024x768 (again, use the resolution that's best for you)

Next run:
gksu gedit /etc/initramfs-tools/modules
This will open up modules in gedit for you to edit.
At the end of the file, paste the following line
uvesafb mode_option=1024x768-24 mtrr=3 scroll=ywrap (mind the resolution)

Next run:
gksu gedit /etc/initramfs-tools/conf.d/splash
Will load a blank file add this line:
FRAMEBUFFER=y

Save the new file and close gedit Then run:

sudo update-grub2; sudo update-initramfs -u

This will make your system use the framebuffer driver for bootup but it will switch once the OS gets booted.

Thank you for your answer, but I don't want to replace Plymouth with a fbo splash (i did it for mydestop due to nvidia propietary drivers poorly supported by kms).
I want to know if not seeing any splash is a bug for Eeepc 901 ?

Its not replacing plymouth, its changing the driver used to load plymouth with. If you get no splash at boot then the video driver hasn't loaded. The splash shows at logoff because the driver has loaded so can be used. This is a common bug with lots of video drivers and especially affects nvidia and ati but can affect some intel chips which eeepcs use as they are cheap and low powered.