There have been reports of iPhones been infected by worms. Currently, there is a new iPhone worm, which is more malicious than in the recent past.
The new worm is called "Duh" or "Ikee.B", and it uses the exact same vulnerability as the first one. The fix is thus identical – change the root password in the SSH application to something other than the default, which is "alpine". as reported by "Marshable"
Click here (http://mashable.com/2009/11/23/iphone-worm-malicious/) for full details.