If true this would be very significant, because it would mean that the very archaic Denisova mtDNA reported in the new Nature paper is not really archaic.
Anyway, here's an excerpt from the paper:
The recognition of the Neandertal inserts in the Denisova sequence changes the reading considerably and indicates that the sequence before the insert at 16194, perhaps ending at 16181 is corrupt either from degradation or during preparation for sequencing. There may be another explanation for the lack of sequence alignment before that location and the substantial agreement after it. Nevertheless, this finding argues for modern human status of the Denisova sample and against a new species designation as suggested from the original analysis (Krause, et al., 2010). Variations in mtDNA in populations and their significance given the natural history of mitochondria have been noted by Ballard and Whitlock (2004) with a caution of their use to build phylogenetic relationships.
A NOTE ON THE DENISOVA CAVE mtDNA SEQUENCE