Rosh Hashana is often a time where many call for Jews to do more Tikkun Olam. Tikkun Olam is a major Jewish value, and literally means "heal the world." This year's issue (besides the Monsey Chicken Scandal) was Global Warming.
Aaron Freedman of 52Portions used the story of Jonah, which is read as part of the Yom Kippur service, as a jumping-off point to talk about Gore's crusade to save the world from itself. I really like this interpretation, and I think that the analogy works really well, except for maybe the whole "called by G-d to rebuke the people of Nineveh" part.
Luke Ford attended a shul where the rabbi spoke about Global Warming, while More Torah and Radical Torah provided divrei torah* on the subject. Found here, and here respectively.
Global Warming was by no means the only issue discussed during Rosh Hashana services. As Rosh Hashana fell on a Saturday this year several shuls (including mine and Semgirl's) discussed the fact that shofar is not blown on Shabbat, and what that means for the year.
Another big issue? When davening ended. It was mentioned by Michelle, Dov Bear, and again , bangitout, and us, and well, you get the idea.