AdWords announced this past week that in mid May they will be changing the way they use exact match and phrase match keywords for ad delivery. In the very near future, AdWords will imitate adCenter in using plurals and misspellings of words you have set with these selected match types in addition to the specific words and phrases.
Google has stated that:
“Starting in mid-May, phrase and exact match keywords will match close variants, including misspellings, singular/plural forms, stemmings, accents and abbreviations. Based on our research and testing, we believe these changes will be broadly beneficial for users and advertisers.”
You can read the full article and see some examples of this new behavior on the AdWords blog.
As Google feels that they can identify the intent of a search from the query and search history, it makes sense to deliver ads to users when their is small variation and even though the specific keywords may not be in an advertisers keyword list. I consider this enhancement good news, and one of the things I particularly liked about Microsoft adCenter which supplies the pay per click ads for Bing and Yahoo.