There is definitely a role for QA and, in my experience, makes quality more effective as a while when QA is involved the planning, designing and implementation phases.
Typically, in the design, planning and implementation phases, QA can/should be:
- Creating a comprehensive test strategy for the feature/enhancement (identifying user scenarios, edge cases, data requirements, etc)
- Outlining feature acceptance criteria and critical path scenarios with Product Management and Engineering
- Pushing quality process and best practices with PM and Engineering
- Collaborating with other stakeholders (Support and Consulting teams) to ensure that as many test scenarios are included in the strategy as possible
- Learning the implementations (technical implementations) engineering will put in place to ensure system testing is done where needed