Like LOL, like, entrenched in all kinds of sentences, used subconsciously, and difficult to parse the real meaning of without careful consideration, has all the hallmarks of a piece of grammar – specifically, in the pragmatic department, modal wing. One thing making it especially clear that the new like is not just a tic of heedless, underconfident youth is that many of the people who started using it in the new way in the 1970s are now middle-aged. People’s sense of how they talk tends to differ from the reality, and the person of a certain age who claims never to use like “that way” as often as not, like, does – and often. As I write, a sentence such as There were like grandparents and like grandkids in there is as likely to be spoken by a forty-something as by a teenager or a college student. Just listen around the next time you’re standing in a line, watching a talk show, or possibly even listening to yourself.
Just goes to show how complex and deep language can be. This is a good, detailed article on the changing use of the word “like”, which, despite its length, doesn’t even touch upon another now-common use of the word “like” that has even transcended borders and languages: Facebook’s “like”, which has become a noun in several languages – including my own – and carries with it a new verb meaning: to click that particular Facebook button.