It's pretty amazing from Safari to plugged in iPhone in iOS6 using the new remote debugging. I have to mention coda2 & diet coda airpreview for iPad specific live debugging too, and Adobe's new edge inspect works well too (I've been using all three today for a responsive iOS site)

http://www.mobilexweb.com/blog/iphone-5-ios-6-html5-develope... (see last point) http://teamsoell.com/andy/dietcoda http://html.adobe.com/edge/inspect/