Keir Thomas has released a new book (January 2009) , Ubuntu Pocket Guide and Reference and interestingly a pdf version is freely available for download.
I have taken a brief look at the PDF and it contains some interesting information and there are chapters on the command line interface (bash) and security, including encryption.
I am fairly new to OpenVZ although I have played with it on Centos. I really like OpenVZ, it seems fairly straight forward and "containers" or guests are light weight and easy to deploy. Backups are much smaller the saving a 5 Gb VMWare disk ....
I have been waiting for OpenVZ to be ported to Ubuntu (I seem to spend a lot of time on Ubuntu).
Well, it is here and they have ported OpenVZ to current kernels
Previous kernels are broken :(