The ATI installation script fails with a "signal detected" issue. This is on the root partition (JFS), so it's not a remote/local partition problem I don't think. This happens in the terminal and from the recovery console.
Now I can't boot into Ubuntu without fglrx being already installed, because of the classic problem with xorg not being compatible with X1400 cards, and the ati default display driver crashing X on boot.
I can't get Envy to work at the recovery console, it errors out with "destination disk is full" type errors when writing to /tmp, as though it's read-only, which doesn't make sense since that's still on the root partition too.
It looks like I'm going to have to manually install the old repository fglrx and start from there.