What is the 10th US Constitutional Amendment, in theBill of Rights?

The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.

What is the meaning of this Amendment in the Bill of rights, is it saying that  any powers not specifically laid out in the Constitution do not apply for the states?

It is commonly understood that originally the Bill of Rights was not intended to apply to the states; however, there is no such limit in the text itself, except where an amendment refers specifically to the federal government. wikipedia

Does State Right’s still exist?

Yes, unfortuneately the venacular use of the phrase state’s rights is tied up with Jim Crowe laws of the days of segregation.  States have the rights to make their own laws and govern themselves.

Do State marijuana laws trump the Federal Marijuana Laws?

It’s now settled that state law enforcement officers cannot arrest medical marijuana patients or seize their medicine simply because they prefer the contrary federal law,” said Joe Elford, Chief Counsel with Americans for Safe Access (ASA)

local cops won’t arrest people for possession of medical marijuana, but we still have to worry about federal agents, particularly DEA agents, doing drug raids within the state.

For a local cop state laws > federal laws. So basically if your in California and you got a medical card and you get pulled over with bud in your car and as long as your aren’t smoking while driving the local cop cannot seize your medical bud.

Beyond California

Beyond California, the message should now be clear that hiding behind federal law is no longer a legitimate position to take when considering state-level medical marijuana laws.