The court just dismissed the case, finding the use was de minimis (too small of an issue to worry about), fair use, and actually benefited instead of damaged the copyright owner.
Story: Woody Allen Won Out Over William Faulkner in Court
Court ruling: http://www-deadline-com.vimg.net/wp-...0718212943.pdf
Generally speaking, lawsuits are not filed for using quotes. But context is critical as to why the quote is being used. For example, it may not be wise to use a quote as the central theme of a commercial product. Using a quote to illustrate a point, or to make a common social reference is not going to be a problem.