Found an interesting article that talks about this question. It's worth a read ...
Release Management - QA or engineering?
There seems to be some debate around where in an organization Release Management really belongs. Is release management a function of engineering, or is it a function of quality assurance or quality control? A case can be made for both, or neither.
In the place where I currently work, the release management team is a subset of the QA team. But in my previous organization, the organization is big and the product is complex enough that we had a separate release management team reporting to a separate VP that took care of release management of a set of products.
In any case, the release management team needs to be treated as a separate stake holder so as to ensure effective implementation of processes.