From today's New York Times:
"In the months leading up to Judge Sonia Sotomayor's selection this week, the White House methodically labored to apply lessons from years of nomination battles to control the process and avoid the pitfalls of the past, like appearing to respond to pressure from the party’s base or allowing candidates to be chewed up by friendly fire."
Plainly, we are losing the battle against "like" used as a conjunction (that is, with verbs, adverbs, phrases and clauses) in formal writing.
"Although widely used as a conjunction in spoken English," says Harbrace's Glossary of Usage, "as, as if, and as though are preferred for written English."
The Elements of Style weighs in on the issue as follows:
Like. Not to be used for as. Like governs nouns and pronouns; before phrases and clauses the equivalent word is as.
We spent the evening like in the old days. [should be as]
Chloe smells good, like a pretty girl should. [should be as]
The use of like for as has its defenders; they argue that any usage that achieves currency become valid automatically. This, they say, is the way language is formed. It is and it isn't.
An expression sometimes merely enjoys a vogue, much as an article of apparel does. Like has long been widely misused by the illiterate; lately it has been taken up by the knowing and the well-informed, who find it catchy, or liberating, and who use it as though they were slumming.
If every word or device that achieved currency were immediately authenticated, simply on the ground of popularity, the language would be as chaotic as a ball game with no foul lines.
For the student, perhaps the most useful thing to know about like is that most carefully edited publications regard its use before phrases and clauses as simple error.