Undoubtedly. Will it be compatible? Who knows?
The iMac G5 is THE most finicky Mac for RAM compatibility. THe RAM not onlyhas to be PC3200 DIMM, 2.5V, etc., but it has to have the correct Serial Presence Detect settings -- there is no way to tell by looking at it whether it does or not. Unless the seller knows Macs and is prepared to guarantee that the SPDs are correct for the iMac, it's a cr@pshoot.
I recommend that you buy RAM that is tested and guaranteed compatible (in writing) with your model of Mac, from a reputable seller that offers a lifetime warranty and a no-charge return if it doesn't work.
Thanks
Trevor
CanadaRAM.com