I found a nice howto to prepare an USB Memory Stick as bootable LiveCD for Ubuntu 8.04 on the blog of Ryan Cloke.
The Webserver Apache is successful updated to version 2.2.9. There are several security enhancements and bugfixes in this version.
The Antivirus Scanner for the Mailserver is now updated successful to version 0.93.1. This version contains improvements for scanning HTML and PDF files and various other bug fixes.
Courier Authlib was just updated successful to version 0.60.6.
Apple provided a security release (2008-02) for Mac OSX , which has applied successful to the Mac server today.