I first became aware of the Hexagonismo y Arquitectura blog earlier this week, when I saw it on a list of traffic sources to this site. At first I didn't know what to make of it, being a bit too Iberian for my linguistic competencies, but upon further inspection it seemed to be affiliated with a "Hexagonismo" movement operating out of Ibiza, more of whose work, I think, can be found at Hexperience.org. [Edit 2013-11: This site unfortunately seems defunct at this point.]
This 2001 article from the Colonial Williamsburg Journal offers a fairly eloquent exposition of certain aspects of hexagonal symbolism that are worth noting. I found the hexagons themselves fairly interesting too—particularly in contrast with the rather hexagon-poor architecture of colonial New England that I'm more familiar with. I've never been a great fan of Anglicanism, or High Church aesthetics in general, but the Puritans clearly couldn't design an interesting building if their lives depended on it—indeed, they probably would've interpreted a hexagonal cupola as a sign of idol worship or something.