gistfile1.twig

{% set allEvents = craft.entries.section('events').find() %}
{% set futureEvents = [] %}

{% for event in allEvents %}
    {% if event.startDate | date('U') >= 'now' | date('U') %}
    {% set futureEvents = futureEvents | merge([event]) %}
    {% endif %}
{% endfor %}

{% for date, events in futureEvents | sortByField('startDate') | group('startDate|date("F Y")') %}
    <h1>{{ date }}</h1>
    <ul>
    {% for event in events %}
    	<li>{{ event.title }}</li>
    {% endfor %}
    </ul>
{% endfor %}