Lets see what the ibookhacks actually did.
According to
this it was included in 3.6-release.
These hacks were included in the xenocara packaging. Here's the link to the
log for the xenocara version of radeon.h, and here's the link to the
log for the xenocara version of radeon_driver.c.
As BSDfan states, the update to 6.9.0 looks like it removed the hack.