We had a really nice meal with some old friends over the holidays. I hadn't seen Denise and Terry since, I don't know when. We have some odd connections. I got chatting with Denise who is picking away at a BA in theology from Tyndale. She mentioned that in the Alliance (we met in the Pentecostal church and she was instrumental in my coming to Christ) church where her family calls home, she has heard a fairly consistant complaint that the Vineyard believes in adding to the Word of God. She wanted to hear my take. I think it is a good question and I imagine that you could accuse a lot of pentecostal/charismatic groups of the same thing. But I'm not convinced it sticks.
There are two sense of this that need to be dealt with: 1) relationship to Scripture and 2) the practice of prophetic giftings. The first is easy for the Vineyard. If you read our statement of faith it is pretty clear that we affirm a closed canon of scripture. So if the concern is adding to the Scriptures then it is unfounded.
The second is a bit harder to pin down. I know there are Vineyards (and other churches) that hold prophetic utterances, especially public utterances, as at least equal with scripture. This might not be official but it is done in practice. But overall the theology of the Vineyard isn't very favourable to this stance.
One of the key distinctives about the Vineyard is a notion that everybody plays. What is meant by that slogan is that we try not to elevate offices in a way that they lord it over the church. In fact we regularely discourage giving directional words to other people. The reason is that we believe each of us hears from God in our own ways and that the gift of prophecy is really a gift of hearing the Shepherd's voice. Further, the office of prophet has more to do with equipping the church to better hear for herself as well as helping the church become equipped to discern (test) prophetic words. In this process of testing prophecy is first of all rooted in a trust of the authority of scripture.
John Wimber would tell us that the Bible contains the Word of God, but not every Word of God is in the Bible. I find this is actually a good balance to the biblolatry that is part of the evangelical culture. It is silly to think that the Bible covers in a plain way all the situtations that life will throw at us. It is always helpful, but this is also a discernment process. The easy test case is slavery, at one point slavery was thought quite compatable with the Biblical texts. This does not mean we have a flexible canon, but rather a maturing relationship to scripture. We read it in our context and find the Bible a faithful witness in our day. For me this is a high value of scripture (much higher than forms like literalism that insist on hammering the scriptures into pseudo-static categories). It values the relationship that the church has with scripture and recognizes that this is process that belongs to the church herself.