Google posted this on their AdWords blog yesterday.
Years ago exact match in AdWords meant exactly that. Your ads only showed for that specific query exactly as you listed it. Over time Google has expanded that and will sometimes show your ads for plural variations, single variations, misspellings, removing or adding symbols such as the apostrophe in "it's" versus "its", and sometimes even abbreviations.
Over the coming months, Google is expanding their definition of exact match again. Exact match variations will now include removing, adding, or changing function words. Function words are prepositions, conjunctions, and words like a or the that don't impact the intent of the search. In addition to that, they will be looking at changing word order. For example, running shoes could now be an exact match for shoes running.
Whether or not this ends up being a good or bad change is something we will have to wait and see. Having to generate a giant list of keywords to target things like running shoes, shoes running, shoes for running, shoes to run in, and every other conceivable variation can be a pain in the ass. That being said, this was kind of the purpose of the phrase match options. Phrase match let you hit all of those close variations.
It all comes down to how good Google is at this, and when it comes to understanding language and searcher intent, they have gotten pretty good over the years. The concern is going to be if they decide things like running shoes for women is an exact match for running shoes but I don't sell shoes for women. Advertisers will certainly get upset if they are paying for clicks that do not help them.
One more reason to make sure you are maintaining a well thought out negative keywords list and keeping it updated regularly in your campaigns.
In my opinion, this is really about driving up the costs of ads. I am not usually a Google conspiracy theorist. I fully understand that Google is not a non-profit organization. They need to keep finding ways to increase revenues and keep their shareholders happy.
A lot of the updates Google makes to AdWords does improve the ROI for advertisers as well as the usability of the platform. This one looks like a straight up money grab.
By expanding the variations on exact match phrases, it will create a situation where there are more advertisers, intentionally or unintentionally, bidding on a lot of queries which will likely drive up the cost of each ad position on the page.
Again, make sure you are constantly monitoring (or your PPC manager is) your campaigns and that you are quickly identifying phrases that you would rather not be bidding on. Get those added to your negative keyword list right away.