Sorry for the lack of updates recently, there just hasn't been any progress in making the GPS-CS1 work with PPC Macs.
However, Leopard is out tomorrow and the latest version of Tiger, 10.4.11, is due any day now.
I will try the GPS-CS1 on 10.4.11 as soon as it is available, if someone else could try it with Leopard and post the results I'm sure many PPC owners will be grateful. And not just PPC owners - since Apple don't appear to have deliberately fixed GPS-CS1 support on Intel machines, it's possible that Leopard or 10.4.11 could break that support. So Intel owners, please let us know if that happens.