If you're a bit late on this article, the new Yongnuo 565EX flash can be triggered by a Canon remote. So questions came up whether the Yongnuo YN-565EX Flash will work with the Radio Popper PX wireless triggers. Indeed it does and i've run some tests. There's no reason it shouldn't because the Radio Popper PX system takes the Canon infrared, does some magic, and then sends the very basic infrared back into the flash. The problem you'll run into is the standard RP shoe mount is not aligned. Never fear as a bit of Velcro will do just fine lining up the infrared ports.
Some of you might be wondering why you would need the Radio Popper system? Well let's start out by saying if you don't shoot in High Speed Sync, then you probably don't need it. You could do just fine with the RF603 triggers and switching the flash to manual mode. Instead of relying on Canon's infrared signals (which requires line of sight and gets pretty spotty outdoors), you could get more consistent results with a true wireless system. The only other benefit to using the Radio Poppers is if you want to control flash compensation straight from the camera (instead of walking up to the flash), or if you are managing power ratios and groups of flashes. If you're a bit new, my suggestion is to just go with the RF603 setup and learn how to work the flash manually. You'll actually gain a good understanding of flash.