Here is a Cnet news article I just read about malware getting installed through apps on windows mobile.
"Once the app is installed the virus wakes up and starts dialing premium-rate numbers like in Somalia and the South Pole, Hering said. He added that victims may not know about the problem until they get their phone bill and see that it's $50 or $100 higher than it should be."
Here is the article
http://news.cnet.com/8301-27080_3-20...=2547-1_3-0-20
One more reason to "Know" what you are installing before just clicking aimlessly at any .cab posted.