I chose the manual partitioning option.
I first created a new partition table.
Then I created a 5 GB swap at the beginning of the disk (RAM is 4GB)
I left a 1 GB gap in the middle of the disk, unpartitioned, to not use up the entire disk.
Then I created a 300-something GB XFS partition at the end of the disk.
Installation continues until grub tries to install and fails. Grub says that it has failed. I opted to continue without installing the bootloader. Upon finishing the installation, ubiquity also crashed, which is what this apport report caught. The real problem appears to be with grub/partman though.
This is ubuntu-oneiric-desktop-amd64+mac.iso from 2011-09-21
This is a MacBookPro6,2
DistroRelease: Ubuntu 11.10
Package: ubiquity 2.7.34
ProcVersionSignature: Ubuntu 3.0.0-11.18-generic 3.0.4
Uname: Linux 3.0.0-11-generic x86_64
Date: Wed Sep 21 21:34:42 2011
LiveMediaBuild: Ubuntu 11.10 "Oneiric Ocelot" - Beta amd64+mac (20110921.1)
PATH=(custom, no user)
UpgradeStatus: No upgrade log present (probably fresh install)