Explorations with emoji replacement in the browser: http://jsfiddle.net/a4JmQ/

emoji_replace.js

/*!
* From: (c) 2012 Steven Levithan <http://slevithan.com/>
* MIT License
*/
if (!String.fromCodePoint) {
    /*!
    * ES6 Unicode Shims 0.1
    * (c) 2012 Steven Levithan <http://slevithan.com/>
    * MIT License
    */
    String.fromCodePoint = function fromCodePoint () {
        var chars = [], point, offset, units, i;
        for (i = 0; i < arguments.length; ++i) {
            point = arguments[i];
            offset = point - 0x10000;
            units = point > 0xFFFF ? [0xD800 + (offset >> 10), 0xDC00 + (offset & 0x3FF)] : [point];
            chars.push(String.fromCharCode.apply(null, units));
        }
        return chars.join("");
    }
}

var $body = $(document.body),
    text = $body.html(),
    emojiHex = "1f449",
    emojiDescription = "<i>white right pointing backhand index</i>",
    emojiCodepoint = parseInt(emojiHex, 16),
    emojiRegex = new RegExp(String.fromCodePoint(emojiCodepoint), "g");

$body.html( text.replace(emojiRegex, emojiDescription) );