One reason the Rick Warren thing is a big deal is because, after Bill Clinton, the gay community is unusually sensitive to getting the shorter angle of presidential triangulation. It is hard to overstate the optimism and excitement that gays and lesbians felt in 1992. But the optimism deflated spectacularly after "Don't Ask, Don't tell" and the Defense of Marriage Act, not to mention President Clinton's sneaky 1996 ad boasting about DOMA, which aired only on Christian radio.
Clinton was willing to say the word "gay" in public and appear in black tie at the Human Rights Campaign dinner, but, in the eyes of the gay political community, his commitment to gay rights vanished both times it counted most.
You can read more about the growing controversy here.