At the end of the day, I think Microsoft walks away from this fairly smug. Rumors regarding the deal state AOL not only received preferred placement on Google (which some find fairly heretical to Google's mission) but also ceded advertising inventory to AOL's sales team (on both AOL, Google and Google publishers' sites). MS ultimately forced Google to buy their own ad revenue at a premium, cede at least partial control of ad sales to AOL, reduce the algorithmic 'neutral' status of Google ad results and distance themselves from at least some of their customers (with AOL as a middleman).
Reminds me of a scene from The Untouchables when the mob shot one of Eliott Ness' FBI agents and scrawled 'Touchable' on the wall of an elevator. Microsoft making Google respond to its competitive pressure makes Google touchable as well. You can only assume this is the first of many strikes by MS on Google going forward...
Update: Marissa Mayer clarifies some of the finer points of the AOL deal on the Google blog (post_here). She states that AOL will not receive preferential treatment on ads (I'm not sure how giving a $300MM credit to AOL doesn't equate to 'preferential treatment' on advertising). Marissa states AOL will continue to have Onebox access (she doesn't clarify if AOL will receive more visibility in Onebox or not). She denies that Google will 'ever' have banner or flashy ads on the homepage or on search results (I assume that doesn't exclude other pages beyond these).