Not sure if this one has been discussed but I have had this issue for a while and now one of my members posted this:
I have a different kind of problem with the iPhone. If I reply to a message or my message gets longer than about 5 lines the screen starts jumping to the top and I have to scroll back down to see the reply or I can keep typing blindly. Everytime I complete a word and hit space the screen drops back down to normal. This is not the only forum this happens on so I assume its a bug in Safari.