This may be true, but I had not heard anything about this phenomena before. I was studying cell biology only last sprig semester and I recall that the textbook [the Cell a molecular approach, Cooper, 2000] did specifically mention that mitochondria was always inherited maternally. That is a book not two years old, so this can't be common knowledge... I have not read the latest edition of the Cell by Alberts et al., but still.
It is kinda strange that some of the mitochondria of the sperm escape into the ovum and actually become the majority (as was the case with the man in the Nwe Scientist article). The ovum is essentially a ready cell, but is haploid. All it needs is the other half of the genome from a sperm cell. It doesn't need mitochondria from the sperm cell, I think, but admittably this creates more diversity.