Bill Maher is seriously funny in this LA Times op-ed about the growing threat of the birther movement. (Maher wrote this before poll results came out showing that a majority of Republicans either don't believe or aren't sure Obama was born in the United States).
This flap might be a deluded right-wing obsession that is a total waste of time, but so was Whitewater, and look where that ended up. A handful of Republican operatives, enraged at Bill Clinton's unprecedented economic growth and budget surpluses, found a woman named Paula Jones, which led to a woman named Monica Lewinsky, which gave me enough material to eventually be able to buy a big house in Bel-Air. Which I'm still conflicted about.
More recently we had the Swift Boat allegations against John Kerry, in which Kerry was accused of volunteering to serve in Vietnam so he could jump in front of a bullet so he could get a medal and then throw it away to satisfy his urge to insult real Americans. This was so stupid that Kerry refused to even discuss it.
And we all know how well that worked out.
UPDATE: This graph shows the geographical breakdown of birthers and fact-based thinkers.