formatting sites for mobile devices

[eluser]bigtimslim[/eluser]
I am getting ready to create mobile versions of a few sites (probably just use a stysheet). I know that you can tell mobile devices to use a specific css file with the following html:

Code:

<link rel="stylesheet" href="mobile.css" type="text/css" media="handheld" />

However, this doesn't work for me when I switch to iphone 3 useragent. From further research, I have read that this way often doesn't work. Any thoughts? Should I just detect mobile with CI and load the needed sheet?