Tony,
My old camera (which is now on the scrap heap) used XD cards but all I did was buy a couple of 1GB SD cards just for the picture frame, one was in the frame and the other was being loaded with different pictures from my PC and then waiting to be used when we got fed up with the pictures and wanted a change.
Even if the Smart media is discontinued, just uplad to you PC from the camera and thensort and make a folder, as I said I do, then copy to the SD card or whatever card your frame accepts.
I tried to find one originally that you could plug a USB stick into but someone said that it wouldbe prone to getting knocked and damaging the contacts on the frame, which would work out expensive.
Any with their own onboard memory to store would need to be connected to the PC to upload everytime you wanted a change. I think the memory card idea is the most convenient.
dave