I just posted this in Media/Journalism, but since it's about blogging, I'll post it here too...

I have a blog about ethical consumerism; I am the sole author. Recently, a company that I blogged about (in a positive light) a few months ago approached me to ask if I would write a post on their upcoming blog in exchange for a linkback (no pay). The subject would not be about the company but about its general field, and I would basically be a guest blogger representing an independent voice. It sounds like their blog will feature content both from independent writers about this field and from company employees and users of its service.

My question is, Is it worth it for me to do this? I'm hesitant about writing for someone that I've blogged about, especially since my own site is a lot about ethics. I don't want to raise any appearance of a conflict of interest.

Any thoughts?