If you are a user of Typekit you might be aware of a small problem reported on the Typekit blog:
Mobile Safari on iPhone OS 3.1+ will crash when rendering multiple weights and styles of SVG webfonts
If you are one of the people who use multiple font weights, I've written a little script to browser-sniff for iOS under version 4 and not include the Typekit embed script.
The first is JavaScript; where you would normally put try{Typekit.load();}catch(e){}, replace it with the first gist.
The second is a PHP version. It doesn't even embed the Typekit JS source if an iOS < 4 is detected, which saves some bytes — useful on a mobile browser, especially if it doesn't support the feature anyway.