I just thought I'd chime in with my recent experience regarding About.com.
I applied for two different Contributing Writer positions. One of which I was extremely well-suited for, the other of which I was reasonably qualified and could pick up as I needed.
They accepted me into a training program for the first position, and I went through the process of writing four articles over four weeks, without pay. They gave me a small list of topics and a little advice, and that was it. I got what clarifications I needed, and set out to deliver the best articles I could. My "trainer" had nothing but praise for me, and any corrections he suggested were minimal and mostly technical. When the time came to submit my revisions, I made sure to hit every point brought up, tighten where needed, and put my best foot forward.
The end result? They decided to go with someone else. Specific quotes included "We reviewed the samples thoroughly with the Guide but ultimately decided it’s in our best interest to work with other writers. It came down to voice and how you were covering the material." and "...some of the info you chose to include and some you chose to leave out in the pieces. Again, a lot of the writing was solid, but we just felt it was best for us to pass and work with other writers."
It felt like I'd been asked to bake a cake of any flavor, given advice on how to bake a very good cake, and then judged by what flavor cake I chose to make. Sigh. (And that position is still listed as open on the site!)
As for the other position? After two months of waiting, I was rejected because they were no longer recruiting.
So that's my About.com story.