The Playstation 3 uses RF (bluetooth) for its wireless remotes. This is great for a game remote, but less convenient for a BluRay player remote, since it makes it incompatible with universal remotes, which communicate using infrared (IR). Sony sells a DVD-style remote, but it also works by RF. Unlike the XBox 360, which uses RF for its controllers but includes an IR port for DVD player style remotes, the PS3 has no IR sensor at all.
However, there is a workaround, because the PS3 also supports wired controllers via its USB ports (which is also how you recharge the controllers). Nyko has cleverly taken advantage of this by producing an IR remote that emulates the USB wired controller. You simply plug a USB dongle with an IR sensor into one of the USB ports, and then you can use the Nyko IR remote--or a Harmony remote, if you teach it the commands from the Nyko.
This works quite well. There are some inherent limitations, however. In particular, this approach means that the Nyko remote is only able to support the commands that you can execute with the PS3 controller, and does not provide some of the additional commands available on the PS3 bluetooth remote. So no power key, angle key, or eject key. But it does emulate all of the digital controls of the PS3 controller (i.e. everything but the analog sticks), which makes it fine for controlling the player. I don't mind the lack of a power control as I leave my PS3 on all the time anyway, since it isn't noisy like the XBox 360, and I have set it to donate unused computing power to the Folding@home scientific project. And if I'm going to eject a disk, I have to walk over to get it anyway, so I might as well push the button on the PS3.
I had good success teaching the Nyko's IR commands to a Harmony universal remote. This mostly went well, although the square command seems to be difficult to learn properly, and took a couple of dozen takes to get it right.