I have a web application that uses TinyMce to allow rich text editing. Some of my customers are desperate to get it to work on iPad (which doesn\'t support contenteditable and t
Write my own iPad app. This isn't really workable because it's a big complex app with loads of HTML and javascript and I would have to rewrite it all
Not necessarily true. You can embed the working part of your web app in a UIWebView component, which is basically Safari embedded in your app, and handle the not working part in the app (providing content). It would require work for sure, but maybe a lot less than rewriting the whole app for iPad.
As of June 2011, it looks like there may be support coming in iOS 5
http://www.tuaw.com/2011/06/08/will-ios-5s-safari-deliver-better-support-for-web-editors/
this observation (that it's working in the beta) has been confirmed by a colleague of mine too.
At to this point there are no browsers on the ipad that will allow RTE. Actually there is only one phone giving full browser support for RTE (sry, i forgot the name of the phone). Therefor, i think you almost showed all possible solutions (jv42's suggestion excluded) yourselve.