I would now be surprised at all if 10.6 is Intel-only and all cocoa.. apple has been trying to make devs migrate to Cocoa from carbon with bigger and bigger sticks with nails in them.. dropping carbon 64 was a big one.. dropping PPC forces ppl to buy new hardware and cleans up these "ultra dense universal binarys" where a dev has to have support all these skews... PPC 32, 64, intel 32, 64..
Yeah, there's one dev in particular that has been lousy about moving to cocoa and 64 bit...they do both pro apps and stuff for newbies...I think it's something like..."apple"?
The G4/G5's were fantastic cpu's in their time, and have served us well, but yes, it's time to let them go out with a bang.
In their time? The quad G5 is still a great machine, and more powerful than many of the machines apple is shipping now.