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>