Well it is time to submit images to calendar companies for the 2011 calendars (until June). I learned a bit about this in Jim Zuckerman's "Making Money with Your Photogrpahy" course through BP. While the Photographer's Market has a few companies listed, the better source of publishers is found via the web or at your local bookstore (later in the year though). Anyway, finding publishers for your type of work appears to be the trick. So far I have found going to calendars.com and finding calendars with my type of images in them is the best way. I would also advise keeping a record of the companies you find along with pertinent info. I am using a spreadsheet for this. Once you find a company you can generally find their submission guidelines buried on their site - I record this as well. I can tell this is going to take some work. Next will come selecting appropriate images and sending them. It is important to make sure the publisher's markets and you images are a good fit.
Image: I found this driving along the back roads where I live. Hard to resist those colors. This should make a good calendar image. They like bright colors and you need to be able to crop it to a square if necessary.