I expect that this event, Talk Marriage, is going to be a very good thing. It takes place in the evening of 7th February 2012, and is free, though you do need to book a place in advance.
The event is ecclesially interesting for two reasons. One of the speakers is a Catholic, a lay Catholic rather than a cleric. The other speakers are leaders in various non-Catholic ministries. For these latter speakers, it is more natural that they should take a lead in a matter such as marriage and not feel dependent on clerical leadership in order to do so. For Catholics, that lay people should be the leaders in the promotion of Catholic ideas in the public sphere, leaders in their own right and not through dependence on the clergy, is a relatively recent insight into what we would call the "lay apostolate".
The second reason comes to mind during the Octave of Prayer for Christian Unity. Talk Marriage is indeed an exercise in a particular form of ecumenical activity, namely common activity in the public sphere in favour of a teaching and values held in common. It is an example of a dialogue of life. It is the type of ecumenical activity that can often be lost to sight.