A friend of mine emailed me a quote from David Spangler who writes, "Blessing is not a technique we perform but a presence we embody. It is not an act we do to someone or something, but a relationship we form with them that enables us all to be embraced in the presence of an unobstructed world."
My wife calls housecleaning "Blessing the Home", which I think she got from the Fly Lady. Cleaning is a part of blessing indeed in that it sets up a sacred relationship between the self and the body, the home, the yard/land...whatever it is we are cleaning. It is a way of being in sacred harmony with the environment.
When I say to someone, "Blessed Be" I am encouraging them to become the best they can be in sacred harmony with all that is. This harmony is something that requires thought and attention. And if we put all our attention into everything we do, then not only are we in the moment, the now, but we are in blessed harmony.