Google announced a new program for Blogger blogs with a Gadget for "Advertise Products." If the blog has an active AdSense account, writing a blog post that contains copy for an available advertiser will result in the "Advertise Products" Gadget appearing with the option to add it to the blog.
From the Gadget, the available advertisers will appear. Select one, then publish the blog post. For blogs without an active AdSense account, an AdSense account will need to be setup. All of this can be done from the Google's Affiliate Publisher page.