Quoted from Jim Dixon above: "Remember Don Imus'...".

That should of course read Don Imus's. Only plurals ending in "s" and, for some reason, biblical characters have the possesive apostrophe at the end of the word. Singular words ending "s" require the "'s" ending

One thing about the greengrocer's apostrophe is the oft seen "potato's" which is correct as the apostrophe indicates the missing "e".