|And no wonder, with all this|
confusion going on.
No, seriously: Grammar Girl says not to end a sentence with a preposition if the preposition is unnecessary (her example is, "Where are you at?", in which the "at" is already implied and need not be spoken). Tina Blue of Homestead.com says to do whatever sounds natural. Jack Lynch of Guide to Grammar and Style says re-word if you can, but not to the point of making your sentence sound all clunky. Grammar Mudge more or less agrees, saying to avoid ending a sentence in a preposition if there is a "graceful alternative". Cliffs Notes says, basically, go ahead. Daily Writing Tips actually says "Go ahead." Dr. Winford James has a lovely linguistic explanation that involves the relevant noun phrase making an invisible copy of itself, since the noun in this instance must do double duty as a subject of a sentence and object of a preposition. If you only want to click on one of these links, this would be my recommended one. One of his examples is "The topic wasn't worth speaking on", which could be logically re-worded to be, among other things, "This is a topic on which I will not waste my breath" (that's my re-word, not his). But, what "the topic" in that sentence has done is move to the front, so the sentence is to be understood as "The topic wasn't worth speaking on (the topic)". Which would be redundant and silly if actually written out.
Among the sources cited is some discussion of phrasal verbs ("cheer up", "run over", "write out"), which appear to end in a preposition but don't, because the preposition is now part of the verb. And then there are prepositions that double as adverbs that can throw people off because they appear incorrect but aren't.
The over-arching advice that I read many times over, however, is this: If you are in a formal writing and/or speaking situation and your writing/speaking my be read/heard by someone who believes in the "no final preposition" rule or the aforementioned Grammar Nazis, then it's time to re-think, re-word, or scrap the sentence and start over. Otherwise, in blogs, Facebook, casual conversation, non-Nazi parties, or that soon-to-be bestselling novel you're writing, carry on and have some fun with it.
Were you taught not to end a sentence in a preposition? (I wasn't, by the way.) Do you do it? Avoid it? Not care one way or the other?