Version:           1.11.1 (using 4.2.1 (KDE 4.2.1) "release 106", KDE:KDE4:Factory:Desktop / openSUSE_11.1)
Compiler:          gcc
OS:                Linux (i686) release 2.6.27.29-0.1-pae

Basically the short description already tells the full story. If you use Kontact on a notebook you might wish to protect all data trusted e.g. to the address book or stored in KMail against unauthorised viewers in case your machine is "found" by someone else. The only solution I have found so far is to encrypt a complete partition. To me this seems oversized and too time-consuming a solution since I assume that Kontact stores all data to a single file which could easily be encrypted (like a text file in OOo-Writer).