Shared Memory and Xorg.

[Sean Bryant]

I tend to visit Opera's Desktop team blog to see what new features are 
going to be in the next release of the Opera browser. And one 
interesting tid-bit was:
"Added Shared X memory. Should now be quite a bit faster"

And beneath this note was:
"Note: On FreeBSD shared memory doesn't work by FreeBSD design. You need 
to run this as as root:
# sysctl kern.ipc.shm_allow_removed=1"

What exactly does this mean. And is X shared memory special shared 
memory in anyway?