Many people at WebmasterWorld are reporting that many of there "inactive keywords," the keywords that were very low quality ads and removed from displaying on Google.com, have been set to "active" once again. One member reported having about 9,000 inactive keywords and now they are down to 1,804 inactive keywords, and they have done nothing to encourage the change. Others are reporting similar behavior in their Google AdWords accounts.
Forum discussion at WebmasterWorld.