Initial support for SD card has just been pushed to github repo.
U-Boot 2012.04.01-00479-gb58d9ae-dirty (Jun 20 2012 - 11:47:13)
DRAM: 128 MiB
WARNING: Caches not enabled
MMC: CAPS: 00000000
bcm2835_sdh: 0
Using default environment
In: serial
Out: serial
Err: serial
Net: Net Initialization Skipped
No ethernet found.
U-Boot> mmcinfo
Device: bcm2835_sdh
Manufacturer ID: 1b
OEM: 534d
Name: 00000
Tran Speed: 25000000
Rd Block Len: 512
SD version 2.0
High Capacity: No
Capacity: 1.9 GiB
Bus Width: 4-bit
U-Boot> fatls mmc 0
16528 bootcode.bin
127 cmdline.txt
314691 loader.bin
2047848 start.elf
181196 kernel.img
5 file(s), 0 dir(s)
U-Boot>
