For the sake of completeness, I recieved the following from the Terrasoft YDL team.
Nvidia is simply not proactive with support for PowerPC Linux. ATI is coming
forward now and beginning to work with us, but as it stands, not a great deal
has been done to date. We have very limited support (2D only) for most Nvidia
Love to help, but not certain if we can demonstrate a business case strong
enough to cause them to offer binaries or open-source drivers.
Looking forward to hearing from IBM and Apple.
Thank you for your time,