On May 12. 2009, the Montana Firearms Freedom Act was signed by Montana Governor Brian Schweitzer and goes into effect Oct. 1, 2009.
The Tennessee Firearms Freedom Act (HB1796/SB1610) was passed on June 3, 2009. Returned without the Governors signature on June 22, 2009. It went into effect on June 29, 2009.
So while Montana was the first to pass such a law, Tennessee was the first to have the law go into effect.