Ann Friedman has a great column on the subject of identity and solidarity in politics, pivoting off the Clinton-Obama race:
After all, Clinton and Obama and their supporters aren't playing "identity politics" any more than John Kerry's supporters did in 2004, or George W. Bush's did in 2000. It's absurd to suggest that the Andover-Yale-Harvard-bred Bush adopting a swagger and thickening his Texas accent, or John Kerry riding a borrowed Harley onto The Tonight Show set, was anything other than identity politics. And after several early primaries, as it became clear that white men most strongly supported John Edwards, nobody accused them of playing identity politics. Nope, that distinction is reserved for people who have historically not been in positions of political power.
Well said. Given that most people don't have particularly fine-grained or coherent opinions about political issues, questions of identity and solidarity are destined to play a large role in voting behavior. But certain efforts to mobilize concepts of identity are stigmatized, while others are treated as just plain ol' politics.