Located in ppa:linaro-maintainers/tools can be found the newest version of live-build, a45 with the following linaro features applied:
1) armhf support (both native and cross) 2) linaro meta bld information as was discussed at 4Q11 Linaro Connect 3) cross support using multistrap
Live build a45 supports Maverick, Natty, Oneiric and Precise. With you are you able to build your own images native on an armel or armhf host or cross using either an i386 or x86_64 host creating either armel or armhf targets.
For image targets up to oneiric, one is not able to cross assemble the ubuntu-desktop image. However with precise all linaro images including the ubuntu-desktop image can be cross assembled.
Enjoy!