Nvidia changed their license almost 4 years ago and the in-tree license no longer reflects their licensing terms. Their original license prevented you from having more than 1 copy of the same version of the Nvidia driver installed across all computers you own at any given time and made no mention of their FreeBSD driver in their exemption. Their new license permits use on multiple computers and includes FreeBSD.
Added NVIDIA-r1 and updated the ebuilds.