Ok, this one is badly documented. Even the kernel docs are outdated.
Here's how to start using zram on Fedora 16:
# get rpmfusion: http://rpmfusion.org/Configuration
...
# install the staging kmod
su -c 'yum install kmod-staging'
# get zram running (aha!)
su -c 'modprobe zram zram_num_devices=4'
# define the block's …