There are several adsense plugins for Wordpress available that allow you to place adsense ads in your posts without too much work, but they all require you to add some form of code / call into the body of your post to get the ads to appear.
Donncha's links led me to this plugin which does away with that issue:
Biggnuts » Adsense Injection

"My new Adsense Injection plugin just takes a random paragraph break in your article and inserts adsense code. It does one per story. It lets you pick how many total ads to do (0-3) and it lets you pick the formats and colors you want it to randomly select from."

I just installed it on a blog to see what would happen and it's pretty impressive!