Installing Ubuntu 9.04 (Jaunty) on an Acer Aspire One (Model D150) worked quite well. I had to use an external USB CD-Rom Drive as the Aspire One does not have a built in drive, but after enabling the “Press F12 to choose boot device” menu in the system BIOS I was able to boot off of the external USB CD-Rom drive.
Ubuntu worked well with all the major hardware (video, wifi,wired-ethernet, soundcard, and webcam) and the only hiccup was with the built in microphone, which did not work out of the box (the microphone jack would work, just not the built in microphone.)

To get the built in microphone working, I had to install the latest version of the ALSA driver following the instructions I found in post 28 on this thread, as copied below:

So I downloaded alsa-driver-1.0.20.tar.bz2 from

http://www.alsa-project.org/main/index.php/Main_Page

I unzipped the package, I entered into the main directory of the package and then I typed:

sudo apt-get install build-essential ncurses-dev
./configure –with-cards=hda-intel
make
sudo make install

Then I edited /etc/modprobe.d/alsa-base.conf and I added at the end of file the line:
options snd-hda-intel model=acer-aspire

After the reboot I adjusted the audio preferences in this way:

Device: HDA Intel (Alsa mixer)
Preferences: The first 3 items and last 2 items (Front Mic is disabled!!!)
Input Sources is set as default at Mic (not Front Mic!!!).

Finally check that System->Preferences->Sound->Sound Capture is set to “HDA Intel ALC272 Analog(ALSA)” not “ALSA”