A new hymnal -- or at least ready-to-reprint hymns -- is one of the pre-conditions (among many) I see for Unitarian and Universalist Christians growing new churches. Singing the Living Tradition doesn't have the corpus of hymns needed for a rounded Christian life, other denominational hymns often have their own limitations and besides -- as I've written before -- we're effectively between hymnal generations meaning other options are already several years old.
Besides, having a single current hymnal is a strange place for Unitarian Universalists to be. Both Unitarians and Universalists had a wide choice of hymnals in the past, and today the British Unitarians and Free Christians -- only a few thousand strong -- commonly use one or both of a choice of two hymnals. We could do better, but I suspect that local hymnals, rather than additional UUA-sponsored hymnals, will be the more likely outcome. Or, alternatively, a church could have their own set of hymn images to be printed in the order of service. The familiar Frankenstein arrangement of hymns photocopied, trimmed, reproduced (often badly) and tipped-in is a bore.
I've reviewed some of the options, but I clearly don't have a gift for the work of typesetting hymns. For one, I don't read music at all well. But I have been tempted by the open-source Lilypond, a music "automated engraving system", for Linux (current), Mac OS X (to 10.5) and Windows (to XP). Add a template from HymnWiki.org, perhaps edited within something like Frescobaldi and you have something like a workflow.