The piece Sullivan links complains that "NPS has also ordered bronze plaques with verses from Psalms placed at canyon overlooks, truly emphasizing what a Judeo-Christian religious experience the view can be." This is at least misleading if not actually false. The fact is the plaques were placed there 30 years ago by the Evangelical Sisterhood of Mary, a German protestant service organization. The Arizona chapter of the ACLU protested in July, 2003 and the plaques were removed (according to a report from Christianity Today).
After a letter and email campaign, spearheaded by radio talk-show host Dennis Prager among others, the plaques have been restored. So this is not some new putsch of the Evanegelical Right to impose their views on the rest of the country. In the words of Donald W. Murphy, the Park Service's director, in his letter requesting the return of the plaques after they had been returned to the Sisterhood, this was a "return to the historical situation that had been in place".
Now, I have concerns about government involvement in creating intellectual standards especially those that impact science, religion and history. But it seems fairly innocuous to have a privately funded plaque giving glory to God in a fairly generic way, especially since one of our oldest national symbols does exactly that. The Liberty Bell in Philadelphia has the following quotation from Leviticus 25:10, "Proclaim LIBERTY throughout all the Land unto all the Inhabitants thereof."
And, for those who want equal time for other religions, they already have it. As the Christianity Today article remarks:
After all, the Grand Canyon is absolutely full of religious imagery. Buttes are named after Hindu and other religious gods and figures: Isis Temple, Wotans Throne, Zoroaster Temple, Krishna Temple, Holy Grail Peak. The oldest geological layer seen at the bottom of the canyon is called Vishnu Schist.