Reports from WebmasterWorld show that dozens of advertisers have noticed and reported drastic and incredible increases in the cost per click of the keywords in their campaigns. Keyword price inflation examples posted include $0.05 to $5.00, $1.00 to $5 - $10, $0.51 to minimum $6.24, $0.17 to $5.00, and so on. These price increases were noticed overnight by many people, so it does not seem to be a slow, long term change that went from $0.05, to $0.25 to $0.50 to $1 and so on, but rather $0.05 to $5.00 overnight.
AdWordsAdvisor replied but did not really have more detail outside of the quality score with landing pages system. But I suspect we will hear more about this sooner than later.
Forum discussion at WebmasterWorld.
