Pretec has today announced the highest capacity SD card to date, their new 8 GB SD-HC. This new card is twice the capacity of cards announced by Panasonic, Toshiba and SanDisk and means that SD cards will soon be available in capacities as high as the largest CompactFlash cards. Pretec's press release doesn't reveal very many details other than compliance with the SD-HC specification (which has a maximum throughput of up to 20 MB/sec; we expect the throughput of this card to be significantly lower). The Pretec 8 GB SD-HC card has a 'sampling price' of $299 and should be in mass production in the last quarter of this year.
http://www.dpreview.com/news/0609/06090101pretec8gbsdhc.asp
http://www.dpreview.com/news/0609/06090101pretec8gbsdhc.asp