Currently as of R1.4 the bug ships with RedBoot. I'm not a huge fan of RedBoot and decided that i would patch U-boot to work on the Bug. There is still some bugs but its stable enough to flash over RedBoot. I would only do this if you know what you're doing.

Download and patch
[cmw@xling]$ wget bug.cmw.me/u-boot-1.3.2.tar.gz
[cmw@xling]$ tar -xzvf u-boot-1.3.2.tar.gz
[cmw@xling]$ wget bug.cmw.me/u-boot-bug.patch
[cmw@xling]$ cd u-boot
[cmw@xling u-boot]$ patch -p1 < ../u-boot-bug.patch
patching file MAKEALL
patching file board/bug2/Makefile
patching file board/bug2/config.mk
patching file board/bug2/lowlevel_init.S
patching file board/bug2/u-boot.lds
patching file common/devices.c
patching file cpu/arm1136/mx31/generic.c
patching file drivers/serial/arm_dcc.c
patching file include/asm-arm/arch-mx31/bug2.h
patching file include/config.mk
patching file include/configs/mx31_bug2.h
patching file include/devices.h
patching file cpu/arm1136/mx31/serial.c
patching file drivers/serial/Makefile
patching file lib_arm/board.c

Setup your build environment
[cmw@xling u-boot]$ export CROSS_COMPILE="arm-poky-linux-gnueabi-"
[cmw@xling u-boot]$ export $PATH:/home/cmw/com.buglabs.build.oe/build/tmp/cross/bin

Configure and build U-boot
[cmw@xling u-boot]$ make mx31_bug2_config
Configuring for mx31_bug2 board...
[cmw@xling u-boot]$ make

Copy and Flash to the BugBase nor
BUG_RedBoot> load -b 0x100000 -m ymodem -v -r
CC Rawfile loaded 0x00100000-0x0012c1bf, assumed entry at 0x00100000
xzModem - CRC mode, 6(SOH)/176(STX)/0(CAN) packets, 11 retries

BUG_RedBoot> fi unlock -f 0xA0000000 -l 0x40000
... Unlock from 0xa0000000-0xa0040000: flash_unlock_block dev a0000000 block a0000000 size 00004000 count 00000800

BUG_RedBoot> fi wr -f 0xA0000000 -b 0x100000 -l 0x40000
* CAUTION * about to program FLASH
at 0xa0000000..0xa003ffff from 0x00100000 - continue (y/n)?
... Program from 0x00100000-0x00140000 at 0xa0000000: ................

BUG_RedBoot> reset
... Resetting.

Welcome to U-boot
U-Boot 1.3.2 (Jan 14 2009 - 03:18:12)

CPU: Freescale i.MX31 at 513 MHz
Board: Bug2
DRAM: 128 MB
Flash: 32 MB
In: serial
Out: serial
Err: serial
Hit any key to stop autoboot: 0

Bug-uboot> saveenv
Saving Environment to Flash...

Compile Kernel and make uImage
[cmw@xling bug-linux-2.6.27.2]$ make uImage

Flash kernel to Bug nor
Bug-uboot> loady
## Ready for binary (ymodem) download to 0x80000000 at 115200 bps...
CCC763(STX)/0(CAN) packets, 11 retries
## Total Size = 0x001b8ba0 = 1805216 Bytes
Bug-uboot>
Bug-uboot> protect off 0xA0400000 +0x200000
................ done
Un-Protected 16 sectors
Bug-uboot> erase 0xA0400000 +0x200000
................ done
Erased 16 sectors
Bug-uboot> cp.b 0x80000000 0xA0400000 0x200000
Copy to Flash... done
Bug-uboot> protect on 0xA0400000 +0x200000
................ done
Protected 16 sectors
Bug-uboot>
Bug-uboot> reset

Watch it boot :)
U-Boot 1.3.2 (Jan 14 2009 - 03:18:12)

CPU: Freescale i.MX31 at 513 MHz
Board: Bug2
DRAM: 128 MB
Flash: 32 MB
In: serial
Out: serial
Err: serial
Hit any key to stop autoboot: 0
## Booting kernel from Legacy Image at 80800000 ...
Image Name: Linux-2.6.27.2
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1805152 Bytes = 1.7 MB
Load Address: 80008000
Entry Point: 80008000
Verifying Checksum ... OK
Loading Kernel Image ... OK

Starting kernel ...

[ 0.000000] Linux version 2.6.27.2 (cmw@xling) (gcc version 4.1.2) #105 PREEMPT Tue Jan 13 22:12:41 EST 2009
[ 0.000000] CPU: ARMv6-compatible processor [4107b364] revision 4 (ARMv6TEJ), cr=00c5387f
[ 0.000000] Machine: Bug-Labs BUG
..... You get the point

And there you have it.. U-boot on the Bug Base

\cmw