Good news from the copyeditor in my office: The rule banishing prepositions from the ends of sentences is slowly going the way of the dodo bird. It was never a hard and fast rule. After all, we say that this is something I won't put up with and it would be weird to say it any other way. I'm sure there are more examples, you can leave them in the comments section. Anyway, I am all in favor of this new grammatical development except for one thing. It ruins one of my favorite jokes (and I hope I haven't told it here before, but as I once read, if a joke is good, it's worth repeating. I should warn those with delicate sensibilities that although this isn't what I'd call a "dirty" joke, there is some rough language in it. You are forewarned. You should also be forewarned that there are accents in the joke and it's much better if someone is saying it out loud, so you might want to try doing that yourself.
A man in a cowboy hat is wandering around Harvard Square, clearly lost. He stops a local and asks, in a pronounced drawl, "Can you tell me where the library's at?" Well, the Yankee pulls himself up to his fullest height and (cue snotty voice) says, "At Harvard, we don't end our sentences in prepositions!" The Southerner replies, "I sure am awful sorry about that. Can you tell me where the library's at, asshole?"