A big enhancement in OpenOffice.org 3.2 is the support for OpenType fonts. A typical Linux user is able to do most of the tasks with TrueType fonts, however any new exciting fonts available are mostly OpenType fonts. So, OpenOffice.org 3.2 (to be released this month) has OpenType support and most likely Ubuntu 10.04 is going to have OpenOffice.org 3.2.
You can install OpenOffice 3.2 RC (or final, in a few weeks) on your Ubuntu by downloading the relevant archive from download the release candidate. Extract the files and enter the DEBS/ subdirectory. Then, run sudo dpkg -i *.deb in order to install the development version of OpenOffice 3.2. The installed files are located in /opt/ooo-dev3/program/ and you run now run swriter (for Writer). It is quite possible there is already a relevant PPA repository; tell me in the comments and I'll update here.
We test with the Greek Font Society OpenType fonts, which are distributed with the OpenFont License. The Debian/Ubuntu repositories already have the GFS fonts packaged for you. You can either install the fonts with your package manager (open synaptic package manager, search for ttf-gfs), or run from the command line
sudo apt-get install ttf-gfs-artemisia ttf-gfs-baskerville ttf-gfs-bodoni-classic ttf-gfs-complutum ttf-gfs-didot-classic ttf-gfs-gazis ttf-gfs-neohellenic ttf-gfs-solomos ttf-gfs-theokritos
Here is a screenshot of the PDF file of GFS Fonts Sample. With OpenOffice.org 3.1 or earlier these fonts would not appear in Writer and would be replaced with the default OpenOffice.org font. In addition, if you tried to export to PDF, you would get the default font (that is, the OpenType fonts do not get embedded in the PDF file either).
Here is the .odf file of the GFS Fonts Sample. If you load it in OpenOffice.org 3.1, you will notice that the default OpenOffice.org font will appear for each line in the sample file. If you load the sample .odt file in OpenOffice.org 3.2, you need to have the GFS OpenType fonts installed beforehand.
The GFS fonts support Greek, Greek Polytonic and several ancient Greek characters. See How to type Greek, Greek Polytonic in Linux for instructions on how to configure and use the Greek keyboard layout in Linux. Note that to type Greek Polytonic, you do not need anymore to select the Polytonic layout; the default «Greek» keyboard layout has been updated so that you can type Greek, Greek Polytonic and Ancient Greek characters. Ergo, άᾷᾂϡϖϝ€ϕͼϾʹ͵ϐϛ.