As of 1 December 2012, I am no longer accepting unsolicited guest posts. I may accept them again in the future, so please check back then.
Why Are You No Longer Accepting Guest Posts?
I am still accepting solicited guest posts, i.e. where I ask someone to write for me.
That being said, the reason I am no longer accepting unsolicited guest posts is because I was receiving so many entries that required responses that it was taking about an hour per day. Add into that that I was getting a very low percent of usable material, and the benefit of the time is just not worth the cost.