This article is from the alt.usage.english FAQ, by Mark Israel firstname.lastname@example.org with numerous contributions by others.
Yes, yes, we've all heard the following anecdotes:
(1) Winston Churchill was editing a proof of one of his books, when
he noticed that an editor had clumsily rearranged one of Churchill's
sentences so that it wouldn't end with a preposition. Churchill
scribbled in the margin, "This is the sort of English up with which
I will not put." (This is often quoted with "arrant nonsense"
substituted for "English", or with other variations. The Oxford
Dictionary of Quotations cites Sir Ernest Gowers' "Plain Words"
(1948), where the anecdote begins, "It is said that Churchill...";
so we don't know exactly what Churchill wrote. According to the
Oxford Companion to the English Language, Churchill's words were
"bloody nonsense" and the variants are euphemisms.)
(2) The Guinness Book of (World) Records used to have a category
for "most prepositions at end". The incumbent record was a sentence
put into the mouth of a boy who didn't want to be read excerpts from
a book about Australia as a bedtime story: "What did you bring that
book that I don't want to be read to from out of about 'Down Under'
up for?" Mark Brader (email@example.com -- all this is to the best of his
recollection; he didn't save the letter, and doesn't have access to
the British editions) wrote to Guinness, asking: "What did you say
that the sentence with the most prepositions at the end was 'What
did you bring that book that I don't want to be read to from out of
about "Down Under" up for?' for? The preceding sentence has one
more." Norris McWhirter replied, promising to include this
improvement in the next British edition; but actually it seems that
Guinness, no doubt eventually realising that this could be done
recursively, dropped the category.
(3) "Excuse me, where is the library at?"
"Here at Hahvahd, we never end a sentence with a preposition."
"O.K. Excuse me, where is the library at, *asshole*?"
Fowler and nearly every other respected prescriptivist see
NOTHING wrong with ending a clause with a preposition; Fowler
calls it a "superstition". ("Never end a sentence with a
preposition" is how the superstition is usually stated, although it
would "naturally" extend to any placement of a preposition later
than the noun or pronoun it governs.) Indeed, Fowler considers "a
good land to live in" grammatically superior to "a good land in
which to live", since one cannot say *"a good land which to