Given that this library is specifically aimed at mobile browsers, why would you have problems with ie8?

Your other complaints seem inconclusive.

By default, you're wasting 300ms of most peoples time every time they click, this kind of default automatically puts any standard HTML you do on mobile behind native controls.

On android for instance, you should almost never expect your user to double tap as that result is now typically proceed with long presses.

You can load it conditionally for mobile safari only. IE, something like this (using the lightweight head.js loader):

        // load fast click if mobile safari
        if(navigator.userAgent.match(/(iPhone|iPod|iPad)/i) {
          head.js("js/fastclick.min.js", function() {});
        }

or include it in your main compressed js assets but only execute if mobile safari

syntax error, missing ) after the if statement. I always do that too.

I'm sure it won't be too difficult to fix those bugs. What version of FastClick were you using? Were you testing on Android 2? If so I'm working on support for that.