I released initial version of my PostgreSQL 9.0 live CD, which is based on CentOS 5.5. It includes the PostgreSQL related packages that I build for
http://yum.pgrpms.org, along with PostgreSQL 9.0.2.
Details are here:
http://pglivecd.org
http://yum.pgrpms.org/livecd.php
You can add an encrypted home directory while burning iso to USB stick, which helps you to keep your personal data in your USB stick.
This live CD has current versions of many software, like pgAdmin III, phpPgAdmin, Apache, PHP, GNOME, Pidgin, Firefox etc., along with tons of PostgreSQL related packages.
Kickstart file is configurable, so you can also create your own PostgreSQL Live CD's fairly easily.
Please let me know if you have any questions regarding this live CD.