After our brief discussion on Sunday, I thought I would point to excellent articles on this subject (pdf format):
The opening of the eucharistic table to the unbaptized is a practice inspired by the radical hospitality of Jesus. Too often, however, the practice of open communion is adopted casually, without the systematic theological reflection called for by something so central to ecclesial identity and mission. Among the issues the practice raises are (1) its reliance on the claim that Jesus would not have shared a ritual meal with his disciples alone, (2) its departure from the paschal ecclesiology at the heart of contemporary liturgical renewal, which links baptism and eucharist to a post-Constantinian understanding of mission, (3) its failure both to appreciate the pastoral value of longing, and to avoid a modernist commitment to the immediate gratification of individual desire, (4) its naive assumption that boundaries are necessarily inhospitable, and (5) its taking the place of genuine evangelism and public ecclesial witness. This first essay, while not an exhaustive argument against open communion, addresses these critical issues.
Baptism, Eucharist, and the Hospitality of Jesus: On the Practice of “Open Communion” by James Farwell
This second essay engages in an extended dialogue with James Farwell's essay, rebutting many of his arguments against open communion and suggesting a number of theological considerations that might lend support to the practice of inviting unbaptized persons to take communion. The logic of the relationship between baptism and eucharist is discussed in light of the reference of both to the kingdom, and tied to the various forms of Jesus' meal ministry in the gospels. The essay also speculates about what in the present context of Episcopal church life might be driving the trend toward open communion. Finally, there is a review of factors to be taken into account in deciding whether the consequences of open communion for Christian life are acceptable.
In Praise of Open Communion: A Rejoinder to James Farwell by Kathryn Tanner
Here is an essay by one community that practices "open communion" and the rationale behind it.
Come to the Table: a reflection on the practice of open communion at saint benedict’s table by Jamie Howison
an article by Rick Fabian on "First The Table, Then The Font" that also gives a rationale for such open communion.
and a blog post by Tobias Haller on "communion before baptism" in which he argues against such open communion and the devaluing of baptism.