Well I never thought that this might work well, but today I was really impressed by an iPhone application called Mocha VNC. I tried only the Lite Version (because it´s free) and besides missing system keys there´s absolutely nothing to miss.
A fast and easy way to control a box from anywhere.
http://mochasoft.dk/iphone_vnc.htm
Works on iPhone and iPod. Give it a try if you need a fast and easy mobile vnc application.