alika - 1:20 pm on Apr 22, 2011 (gmt 0)
I've always implemented the ads using the second illustration, where the ad is after the first or 2nd paragraph of content. That's where my biggest moneymaker is.
The only rule I think anyone should consider is: what do YOUR users think? Do they confuse the ads with your content?
With this Panda update, it forces everyone to reconsider how the ads are placed with regards to user experience -- regardless of what Adsense peeps even say.