A New York Times article says that Google will be investigated for its $3.1 billion dollar acquisition of DoubleClick to see if the company has violated any antitrust laws.
Last month, Google acquired DoubleClick for $3.1 billion and was challenged by rivals, particularly Microsoft. However, a month later, Microsoft acquired aQuantive for a value of $6 billion.
According to the New York Times article, "Google said it was confident that the deal would withstand scrutiny." I think given recent events and in response to the latest acquisition by Microsoft, this will indeed be the case.
Techmeme has more coverage, as does Search Engine Land.
Forum discussion at WebmasterWorld.