I read on the Oregon State University site that it is a myth that using pine needles as mulch would have much of an impact in lowering the ph of the soil.  The article continues to say, that as this is a myth, one should not worry about planting under pine trees, as the soil will not become acidic and harm plants.

I wanted to ask the question about whether pine needles cause the soil to become acidic in the opposite manner.  Rather, would the acidity of pine needle mulch be a more beneficial mulch in beds where one has plants that favor acidic soil (i.e. azaleas or rhododendron)?  In other words, would a pine needle mulch be beneficial to my azaleas, more so than a wood or other mulch?