+1 for Dave, nice answer.
Something I greatly miss on most QA teams (which is why I tend to call them testing teams instead of QA teams...) is involvement throughout the entire project lifecycle. I think it's important for QA to be involved as early as requirements gathering, partially to help ensure quality of the requirements (Are they complete? Are they consistent? Will IT be able to understand them?) but mostly to ensure that QA really understands the system they are supposed to test. I have been on too many projects where QA gets some software dumped in their lap quite close to ship date and doesn't really know how to properly test the system because they don't know much about exactly how it's supposed to work.
I would expect that a Senior Tester (QA Engineer) would push for early involvement in the project to prevent that type of problem.