I got a KM-200 media player (Sunplus SPCA536) with built -in 512 MB of memory and a expansion slot of SD card. Interestingly, I could not find any specification about how much memory it supports 1G, 2G ??.
http://www4.dealtime.com/xPF-Digital-Media-KM200-512MB
Well, I bought a 4 G Transcend X150 SD card to see if it could handle it. Wow, it immediately regconized and formated the card to automatically. I kept adding video and mp3 files to maximum capacity. No problem. Play them, no problem...Hence my player does support 4G !!!