This report from Zenit, which quotes the Holy Father speaking about St. Veronica Guiliani, once again reminds us that mystics and mystical experience cannot be pushed to the margins of the Church. There is more information about St. Veronica on this blog (Clare's Catholic Clutter).
Many Catholics and other Christians still do not know how to deal with saints like this; they are embarrassed by such things as visions and the stigmata - they would, perhaps, prefer a spirituality where God was not so obvious or personally present, and the kind of theology which rests more on the brilliance of human ideas rather than on the power of the Holy Spirit.
In his address, Pope Benedict is clear that genuine mysticism is not cut off from either the Scriptures or the Liturgy, but is fed by both and can, in some cases, lead us to a deeper appreciation of both. In fact, if mysticism does not do this it is likely false. Having said that, there needs to be better understanding of how we might deal with such things as we read about in the lives of St. Veronica and others, and how we should judge their writings. It is, of course, never obligatory to read and follow such things (not being necessary for salvation etc), but, as some theologians have suggested (e.g. Buby and Rahner), we cannot simply ignore such things or pretend that they are unimportant. In some cases it becomes clear that some kind of response is required when a given apparition or "message" is represented or repeated in ways which are clearly meant to engage our minds and hearts. The late John Paul II's insistence that Our Lady of Fatima had a special part to play in his survival after the attempted assassination is a case in point.