Comment on Web 2 AdSense Theme by SEO Dave.
There’s a file with the cheaper themes (like Web 2) adsense.php that you edit in a text editor or online via the WordPress theme editor, in that file you can set which AdSense ads are shown and their sizes. So with Web 2 etc… you can edit one file (very easy to edit, change a few 1’s to 0’s) and you can easily achieve no AdSense ads within the main content.
The more expensive themes : Talian 5 and Stallion 6 have these and many more settings built into options pages, so rather than editing the adsense.php file it’s all built into the WordPress dashboard (tick boxes).
Stallion 6 is my best WordPress theme, there are a lot of AdSense options built in, you can achieve almost any ad placement you could think of. Currently (May 2011) Stallion is only a 3 column theme, in the next update (probably release in June: all Stallion 6 customers receive a free upgrade) it will have different layouts including 3 column, 2 column (left or right sidebars) and 1 column (no sidebars : they are at the bottom of the content). There’s also around 10 colour schemes with Stallion with more planned.