Found this over on MoDaCo forums -- they have obtained temporary root on the Galaxy Nexus: 03 Nov r1: Superboot - rooting the Galaxy Nexus - Android @ MoDaCo
Superboot is a boot.img that when booted, will root your device the first time you boot (installing su and the superuser APK). No need to flash any partitions, no need to mess around with ADB, no messing with the contents of your data partition, no overwriting the shipped ROM on your device, just boot the boot image using the instructions below and you're done!