engine - 4:28 pm on Apr 18, 2012 (gmt 0)

Here's the official announcement

New matching behavior for phrase and exact match keywords [adwords.blogspot.co.uk]

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.