good question (+1 voted)! there are lots of resources on this but talking from experience the main things I'd cater for are:
- ensure there's no vital flash objects
on the page as it isn't supported by
many mobile browsers (yet?)
- appropriate screen size (using
viewport meta tag)
- keeping in mind that there's no mouse
cursors, meaning no
hover/double-clicks are available any
mouse dragging gestures are different
on touch devices
- remember all pop-ups are open in new
tabs and won't be seen at the same
time as the main window, use
javascript modal divs as alternative
- test all your javascript and css to
ensure everything looks and works the
same (Safari requires -webkit- prefix
for the newest CSS properties)
- create a Home screen icon for your
website (a nice thing to have)
most of these things are covered here
take a look at Safari Dev Center for tutorials/videos/coding how to's etc.