I imagine that the hack would sorta null the overall snapiness of Snow Leopard. I also wonder why one would want this. There are few PowerPc apps that run faster then their Intel counterparts, Adobe comes to mind - but, Snow Leopard and Adobe playing nice seems in question.
No.
The only PPC that could use anything in SL is the G5, but again, the gains would be lost in the translation.
Untrue. However, it won't run, so it doesn't matter that much.
How's it untrue?
While yes, it could run in 32-bit mode on a PPC (if ported) the primary features are 64-bit and Grand Central, which could only apply to a G5.
Grand Central is written to optimise the way code is allocated across multiple Intel processors. How could this possibly benefit G5s?