Awesome news for you guys, I've found a way to enable 3D Vision effects on Crysis 3 MP beta, as developers have censored them on the beta version. The only thing you have to do is open Nvidia Inspector, go to the Crysis 3 profile through the menu on the top and set:
keep the botton line untouched (WKS_FEATURE_SUPPORT_CONTROL_ID2)
After doing that, click 'Apply changes' and play. When you launch the game, if it doesn't automatically take the 3D Vision mode just press CTRL+T and it will switch stereoscopic. Make sure you set 'Frame Sequential' if you're using a Nvidia 3D Vision certified monitor (or a Nvidia 3D Vision 'hacked' one as the Samsung S27A950D with the unofficial workaround). Just leave your eyes fitting to deafult L/R and enjoy the 'Excellent' rated 3D Vision effects! 3D in Crysis 3 is very deep and exciting, it dramatically changes your gameplay!
P.S. if you have a Side by Side 3D Display you only have to modify this setting