No they don't. This is why locks/spriests/fire mages/ferals reapply dots with trinkets and CDs up. You get a full rack of buffed dots.
Also, there is no possible way they will EVER make our mastery strength. Strength is already a main stat. Mastery would then add ADDITIONAL strength on all pieces with mastery. Not to mention the doubt budgeting that secondary gems have. People would end up stacking mastery, and having ludicrous amounts of attack power.