Blogger.com have just gone and made it easy for bloggers using their system to integrate Adsense into their templates by adding new features which allow easy selection and design of ads to blend into their blogs. Bloggers get a more automated choice of size and colors. They offer a variety of ‘match template’ options and ‘blend template’ options.
Users of the system are given the ability to preview how their ads will look before going live with their changes.
Read about it at Blogger Help : How do I put AdSense on my blog?