Worthy of its own post, rather than just an update to the previous...
Forrester's Shar Von Boskirk has posted on the impact of Microsoft's acquisition of aQuantive. There's a lot to consider here, and she outlines it pretty clearly.
I'll leave you with her encouraging close:
[The recent spate of agency acquisitions indiciates that] The shift to online marketing has at last begun. We in the industry have been talking about the shift away from traditional media into online for the last 10 years. But the medium took time to establish its credibility. I think the intensity and price tags of these acquisitions indicates that some very big media and agency firms are staking their bets on online. They've watched the success of Google with search, and want to be in front of the next huge shift of budget into online advertising.
On that note, have a great weekend!