Nope it's been on for a while but it will only work if you have good OpenGL drivers. (About ~50% of Linux users who try are able to view WebGL content from mozilla's numbers).
After fiddling with about:flags and using --ignore-gpu-blacklist on the command line, I got chrome://gpu to report that WebGL is fully enabled. It _still_ doesn't work, with this error reported in the console:
[75:75:1827873622829:ERROR:command_buffer_proxy.cc(110)] Could not send GpuCommandBufferMsg_Initialize.
I will say it's strange that Chrome thinks your computer is incapable but Firefox 11 is able to perform the task. It may be a bug with Chrome worth looking into.
EDIT: I really doesn't work because "NVIDIA cards with nouveau drivers in Linux are crash-prone." Firefox has no trouble, strangely.