Is there TRIM support in OS X 10.6.9 for PowerPC?
A few searches tell me that there isn't good SSD support for power pc macs.

This seems to be mostly a SATA III compatibility issue. TRIM support seems to have been introduced in 10.6.8 but only for Apple-supplied drives. Since Apple was producing Intel-based systems by that point, that is where they focused the support.

There are blog posts where people have talked about specific drives working in G5 and G4 macs but this is notably without TRIM.

OWC has some posts about TRIM and how it isn't for everyone.

The important question is, why do you need TRIM?