As used in Proverbs 29:18.
Where there is no vision, the people perish: but he that keepeth the law, happy is he. (KJV)
Where there is no prophetic vision the people cast off restraint, but blessed is he who keeps the law. (ESV)
Where there is no vision, the people cast off restraint; But he that keepeth the law, happy is he. (ASV)
Where there is no revelation, the people cast off restraint; but blessed is he who keeps the law. (NIV)
Without revelation people run wild, but one who keeps the law will be happy. (HCSB)
The HCSB notes that "revelation" is literally "vision" and there are cross references to Isaiah 1:1 and Nahum 1:1 where the same word refers to the prophecies of those two prophets. Sorting through various commentaries, most take "vision" to mean the preaching and teaching of the Scriptures, with the Christians adding the New Testament while the Jews keep to the Old Testament.
This difference is critical to a church, ministry or mission. If "vision" simply means a purpose statement or other such business "trick" written about by management gurus, then there stands a good chance of there being a problem. Simply look towards the church growth/"seeker-sensitive/Emergent church/Purpose-Driven movement(s) which are following the writings of Peter Drucker. However, we do have a way to check on any "vision" given.
Really a very simple one. Check it against Scripture. See what it leads to. Being "seeker-sensitive" cripples preaching the Gospel, because it seeks to hide the "offensive" bits even though the Cross is an offense to the world! It is different than being contextual, it is throwing away the "inconvenient" bits of Scripture (in practice if not in theory) that "interfere".
Christian groups (using the "wherever three or more are gathered" rule) must fulfill all the tasks of a church as given in 1 Corinthians 12 and Ephesians 4:11-16. For some idea of what is required: And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: (Ephesians 4:11-12) To fulfill the vision (revelation) required by Proverbs 29:18, a Christian group must cover all of these areas, not simply run off after one or two of them and then claim it as a "vision". The pastor or group leader must lead those under his authority to fulfill all of these roles while remaining under his authority, using those that God has given him.