First off, thanks for the feedback last week. Most of the issues were minor and not-too-technical, so they weren't too tricky to iron out.
Another batch of images has been generated with suggested improvements, they can be found at: http://dev.archlinux.org/~simo/archiso_tests/installer/
This time, there are ISO and USB images for both architectures. Once again, I'm looking for testers. So if you have some time to kill, please give 'em a spin and let us know how it goes. Generally speaking the live system should be able to: a) boot and b) connect to a network. If for some reason you can't get it to do one of those, I'm especially interested in hearing about it.
If no major issues can be identified with these, the next batch will be a full-blown core-ftp-i686-x86_64-usb-iso release. Early and Often, as they say.
Thanks for your help!