"PowerPC" was the name of the processor built by IBM and Motorola that used to be the CPU for every Mac prior to 2004. Because they ran too hot, and Motorola had trouble breaking the 1gHz speed barrier and maintaining stability, Apple decided to switch to Intel Processors, which now power all Macs.
Apple stopped ALL support for PowerPC computers and software in 2009 with the release of OS 10.6 (Snow Leopard). Most software manufacturers followed suit. It's nearly impossible to find PowerPC software updates for Macs.
If you have a Mac running OS 10.5 or lower, odds are it's a PowerPC model, and your choices for software are getting more limited by the week. Flash Player 10.1.102.64 is the FINAL build that was made for PowerPC Macs.
That link contains ALL versions of Flash Player 10.1.102.64 as well as 9.0.289.0 for both Windows and Mac.