The intersection between biology and computer science is by far my favorite topic. I wish I would have gone into bioinformatics after my CS masters degree. Both sciences really get the best out of the other.
It depends on what type (and also whether you distinguish computational biology from bioinformatics). The people who create new algorithms for sequence assembly, protein folding, etc. tend to be computer scientists who got into biology. On the other hand, the people who analyze biological data computationally tend to be biologists who got into computing.