A time ago filter with built in timezone conversion from a UTC time source.

timeago.filter.js

.filter('timeago', function () {

    /*
     * time: the time
     * local: compared to what time? default: now
     * raw: wheter you want in a format of "5 minutes ago", or "5 minutes"
     */

    // parse string date to milliseconds
    // Note: months are 0-based
    function parseDate(input) {
        var parts = input.split('-');
        var timeBits = parts[2].split(' ');
        var hms = timeBits[1].split(':');
        // new Date(year, month [, day [, hours[, minutes[, seconds[, ms]]]]])
        return new Date(parts[0], parts[1]-1, timeBits[0], hms[0], hms[1], hms[2]);
    }

    // get difference between UTC and local time in milliseconds
    var timeZoneOffset = (new Date().getTimezoneOffset()) * 60000;

// filter -----------------------------------------------------------------------------

    return function (time, local, raw) {

        if (!time) return "never";

        if (!local) {
            (local = Date.now());
        }

        if (angular.isDate(time)) {
            time = time.getTime();
        } else if (typeof time === "string") {
            time = parseDate(time);
        }

        // convert UTC to local
        time = time - timeZoneOffset;

        if (angular.isDate(local)) {
            local = local.getTime();
        }else if (typeof local === "string") {
            local = new Date(local).getTime();
        }

        if (typeof time !== 'number' || typeof local !== 'number') {
            return;
        }

        var span = [],
            MINUTE = 60,
            HOUR = 3600,
            DAY = 86400,
            WEEK = 604800,
            MONTH = 2629744,
            YEAR = 31556926,
            DECADE = 315569260;


        var offset = Math.abs((local - time) / 1000);

        if (offset <= MINUTE)              span = [ '', raw ? 'now' : 'a minute' ];
        else if (offset < (MINUTE * 60))   span = [ Math.round(Math.abs(offset / MINUTE)), 'min' ];
        else if (offset < (HOUR * 24))     span = [ Math.round(Math.abs(offset / HOUR)), 'hr' ];
        else if (offset < (DAY * 7))       span = [ Math.round(Math.abs(offset / DAY)), 'day' ];
        else if (offset < (WEEK * 52))     span = [ Math.round(Math.abs(offset / WEEK)), 'week' ];
        else if (offset < (YEAR * 10))     span = [ Math.round(Math.abs(offset / YEAR)), 'year' ];
        else if (offset < (DECADE * 100))  span = [ Math.round(Math.abs(offset / DECADE)), 'decade' ];
        else                               span = [ '', 'a long time' ];

        span[1] += (span[0] === 0 || span[0] > 1) ? 's' : '';
        span = span.join(' ');

        if (raw === true) {
            return span;
        }
        return (time <= local) ? span + ' ago' : 'in ' + span;
    };

});