Installing third party iphone apps using a PPC mac?

There are ways, but its a TOTAL pain on a PPC. Just wait a few more days for the new iFuntastic which will be PPC based and MAY have the ability to install apps.

I recommend keeping an eye on things here. I found is the best resource for the latest news and such:

http://iphonealley.com/forums/forumdisplay.php?f=6

For the latest tutorials, check here often:

http://www.hacktheiphone.com