Pattern recognition is very common in machine learning, but there are too many issues behind commercial activities (privacy, security, advertisement...profit-making relevance) take "Optical Character Recognition, OCR" for example, it has been widely used neither in web accessibility nor educational materials. Since the commercial behaviors on the internet/publication have found their settlement in some level. Well... let's pick on Facebook for instance, it has allowing Facial Recognition functionality Jun 2011, despite how much complains or privacy concerns have been raised against it. FB still allowing Facial Recognition not just for user-experience enhancement but the possible revenue$$$ behind it (Ref. :http://www.theregister.co.uk/....../)
Facebook, Google, Twitter, Yahoo!... they have it all, all the necessary datas are there in the data base, just a matter of fact if it's profitable ENOUGH for them proceed the recognition. Sadly we're talking about business here, it's hard to be pro bono without profit making that's why we don't see pattern recognition happening in the main stream. Some of the third party vendors are developing Apps for such needs, but how to make money after all it's still the survival kit.
P.S. - Feel free to drop me a note or any comments below!