While I haven’t seen an any favorable coverage of the birther movement in the mainstream media, even in the more conservative outlets, there is certainly coverage.
When I started my media page series, it took from August 16, 2008 to June 10, 2009 to get a “page full” of articles. The next two page full took just two months each, and and then just one month. This month I have a long page with just the first 8 days of December.
Of course this is not a scientific study. I have better ways of knowing about new media articles than I did before, but still with “birther” a runner up for word of the year, more and more people know about the Obama denialist and conspiracy meme.
That said though, I think birthers in general have less credibility than, say, alien abductee stories.