By Lenn Thompson The only thing holding sauvignon blanc back from taking over the Long Island white wine scene is acreage. There just isn't enough planted, and with the economy where it is, few are investing in new plantings. Eventually it will happen. It has to. The grape shows that much promise here. But for now, those with the vines in the ground are working to establish a regional style — one that is unique and defies comparisons to other classic styles. Paumanok Vineyards 2009 Sauvignon Blanc ($24) is made entirely with fruit from the Massoud's new planting of sauvignon…