Tim Challies posting on "The Gift of Spiritual Discernment" said
"While all Christians are responsible for what they believe, it seems clear that some people are especially gifted by God for this task. This is not merely a gift, but a responsibility. New Testament commentator Lenski says, “Certain difficult cases occur, for which more than common Christian discernment is necessary. False prophets love to use deceptive language. For the purpose of unmasking these prophets the Lord provides this gift and thus enables his church to turn from lying spirits to the one Spirit of truth.” The gift of discernment is the Spirit’s special defense against the lies that come from lying Spirits."
This is first in a series of posts on this topic and his book "The Discipline of Spiritual Discernment" will be available January '08, which going by this post is going to invaluable.